The effect of prenatal exposure to Ramadan on children’s height

Accepted Manuscript Title: The Effect of prenatal exposure to Ramadan on children’s height Authors: Seyed M. Karimia, Anirban Basu PII: DOI: Reference:

S1570-677X(17)30303-9 https://doi.org/10.1016/j.ehb.2018.05.001 EHB 711

To appear in:

Economics and Human Biology

Received date: Revised date: Accepted date:

28-11-2017 30-3-2018 14-5-2018

Please cite this article as: Karimia SM, Basu A, The Effect of prenatal exposure to Ramadan on children’s height, Economics and Human Biology (2018), https://doi.org/10.1016/j.ehb.2018.05.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The Effect of prenatal exposure to Ramadan on children’s height

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Seyed M. Karimia,* and Anirban Basub a

School of Interdisciplinary Arts and Sciences, University of Washington, Tacoma, WA 98402, USA. The Comparative Health Outcomes, Policy, and Economics (CHOICE) Institute, University of Washington, Seattle, WA 98195, USA. * Corresponding author as: GWP 228 Box 358436, 1900 Commerce St., Tacoma, WA 98402, USA. Tel.: +1 2536924945. Email addresses: [email protected] (S. M. Karimi), [email protected] (A. Basu)

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Highlights

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 We examine the effect of prenatal exposure to Ramadan on children’s height.  To control for potential seasonal effects, we pool data from numerous developing countries.  We find that Ramadan-induced nutritional stress during early- and mid-gestation is associated with a decrease in height of up to about 7.3 mm in Muslim male children at age 4 years.  We identify no negative effect in female children.  The effect tends to be stronger in West Africa and Central Asia. It is also tends to be stronger in more religious countries.

ABSTRACT

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We examine the effect of prenatal exposure to Ramadan on children’s height by sex, age, region, and the degree of religiosity. Since Ramadan rotates on solar calendars, we pool demographic and health survey data from numerous developing countries to increase the number of birth years and fairly control for potential seasonal effects. Our results suggest that Ramadan-induced nutritional stress during early- and mid-gestation may negatively affect the height of 3 and 4 years old Muslim male children. The effect tends to be stronger in West Africa and Central Asia. It also tends to be stronger in 1

more religious countries. We do not detect consistent negative effects on height in female children.

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Keywords: Prenatal Exposure to Ramadan, Children, Height, Height-for-Age Z-Score, Religiosity.

1. Introduction

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Maternal health, especially during prenatal period, has a profound impact on the shortterm and long-term health of children (Baker, 1998a,b; Gluckman and Hanson, 2005). Nutrition plays a crucial role during the prenatal stage. Numerous studies, usually employing exogenous natural or human disasters such as famines and epidemics to tease out causal effects, have documented long-term effects on health and cognitive abilities of prenatal exposure to such shocks (Roseboom et al., 2000; Almond 2006). Interestingly, the gestational periods of about three quarters of the 29 million Muslim babies who are born every year coincide with Ramadan, the Islamic fasting month, raising the possibility of unintended shocks to the health of Muslim children. An emerging Ramadan literature has shown that prenatal exposure to Ramadan is associated with lower birthweight, school grade, wage, and adulthood and old age health status (Almond and Mazumder, 2011; van Ewijk, 2011; Almond et al., 2015; Majid, 2015; Schultz-Nielsen et al., 2016).

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We extend this existing literature by investigating, for the first time, the effect of prenatal exposure to Ramadan on children’s height. We also investigate variations in the effect on height by sex, age, region, and the degree of religiosity. Studying childhood height is particularly important because it is a cumulative marker of health that can predict physical health, cognitive and non-cognitive skills, and wealth later in life (Waaler, 1984; Barker et al., 1990; Fogel, 1994; Jousilahti et al. 2000; Carslake et al. 2013, Sanchez 2017).1 While heredity accounts for about 80% of height (Silventoinen, 2003), intrapopulation and most interpopulation differences in height are attributable to environmental elements such as nutrition and disease, mainly in early life including fetal life (Steckel, 1995; Beard and Blaser, 2002). During gestation, critical windows of 1

The dynamics of human capital accumulation, which is self-productive and implies that health status at any time is determined by health status in the past, provides an explanation for the relationship between height and health (Cunha and Heckman, 2007, Heckman 2007). 2

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development of the bones—especially the long bones that lay the foundation for future growth in height—largely coincides with those of vital organs such as the heart and kidney (Appendix A). Therefore, the effect of a nutritional shock at a specific episode of gestation on height may be used to predict long-term effects on vital organs and consequently on important health issues in adulthood such as cardiovascular heart disease and diabetes.2

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Ramadan is a month during which Muslims past the age of duty (which is 9 and 15 complete lunar years for women and men, respectively) are obligated to fast—i.e., abstain from eating, drinking, smoking, and sexual activities during daylight hours. Pregnant Muslim women are exempted from fasting, although they are required to make up for non-fasting after pregnancy. In practice, most pregnant Muslim women fast (Arab and Nasrollahi, 2001; Makki, 2002; Joosoph et al., 2004; Mubeen et al., 2012; van Bilsen et al., 2016).3 Evidence of accelerated starvation, characterized by hypoglycemia and increased plasma and urinary ketones is extensively documented in pregnant Muslim women (Mirghani et al., 2003; Abd-El-Aal et al., 2009; Awwad et al., 2012; Hizli et al., 2012; Khoshdel et al., 2014). It appears that the fetus adapts to fasting conditions since research has demonstrated that symptoms of accelerated starvation have little effect on the fetus’ biophysical profile (Mirghani et al., 2003; Dikensoy et al., 2008; Hizli et al., 2012). The adaptation however can be costly in long term. Mealskipping mothers’ placental adjustments, which are characterized by the release of excessive amount of cortisol, can impair fetal development (Herrmann et al., 2001; Dikensoy et al., 2008; Alwasel et al., 2010). The undernourished fetus may also program its growth to increase its chance of survival by prioritizing the brain, harming the cell differentiation process in other organs such as the heart and kidney. This process can be especially harmful when episodes of undernourishment occur within the critical windows of development of the organs (Barker et al., 1989; Baker, 1998a,b; Barker, 1999; Gluckman and Hanson, 2005; Jaddoe et al., 2006). The latter mechanism, developed in David Barker’s works, is framed as the fetal origins hypothesis (Baker, 1998a,b).

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The effect of maternal nutrition on development of the long bones during their critical windows of development is rarely studied in humans. Nonetheless, it is extensively studied in animals (Lanham et al., 2011). 3 Although there is no empirical evidence, pregnant Muslim women who do not fast may also experience reduced food intake. In Ramadan, restaurants and food shops are usually closed during the daytime in most Islamic countries. At home, pregnant Muslim women usually set the times of their main meals to before sunrise and after sunset when fasting members of household eat. The dietary distortion therefore can be accompanied by a derangement of their sleeping times. 3

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An investigation of the effect of prenatal exposure to Ramadan on height is potentially confounded with seasonal effects since Ramadan is a lunar month and comes about 11 days earlier each year. Thus, its occurrence rotates on the commonly-used solar calendars. Addressing this methodological problem requires data from approximately 30 birth years since it takes about 30 years for Ramadan to complete a full rotation on the solar calendar. A typical survey that collects children’s anthropometric information however includes children who were exposed to Ramadans that occurred in a span of only two to three successive solar months. To address this limitation to a degree, we pool demographic and health survey data from numerous developing countries that have a 10 percent Muslim population. Also, since the exact birth date, including the day of birth, is reported only for children under age 5 years in the data, we do not include older children and adults in our analyses. In the resulting sample, we exploit variation in the timing of exposure to Ramadan during gestation to estimate the effect of Ramadan-induced nutritional stress on children’s height-for-age z-score.

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Our results suggest that in utero exposure to Ramadan may lead to lower height in male children at ages 3 and 4 years, the oldest children in our sample. Specifically, we find that a full 30-day exposure to Ramadan during the 270-day period before birth (or the presumed gestation) is associated with an average decrease in height of about 3.2 millimeters (mm) in 4 years old Muslim male children. When the overall effect is decomposed by trimesters of gestation, the strongest effects are observed for exposure to Ramadan during early and mid-gestation episodes and amount to an average 4.7 mm. In examining exposure during months of gestation, a full exposure to Ramadan during month 3 of gestation has the strongest effect on height in 4 year old Muslim male children and amounts to an average 7.3 mm. We also find suggestive evidence of variations in Ramadan’s effect on height by region and the degree of religiosity.

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The reminder of the paper is organized as follows. Section 2 describes data refinement and organization and the identification strategy and introduces the empirical models. In Section 3, the paper’s main results are presented and discussed. Sections 4 and 5 examine variations of the effect of prenatal exposure to Ramadan on height by region and degree of religiosity. Section 6 discusses policy implications and conclusions of the findings.

2.

Data and Empirical Model

2.1.

Data 4

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We use data on child birth date and height-for-age and mother’s religion collected from 98 demographic and health surveys (DHS) in 37 countries, in our empirical analyses.4 We initially started with 117 DHSs from 45 countries with at least a 10 percent Muslim population. However, we dropped 19 surveys in which no information on children’s exact birth date and mothers’ religion is collected. The remaining 98 surveys provide a pool of 900,811 children from 37 countries.5 In each of the 98 surveys, there are children with and without exact date of birth (DOB).6 Exact DOB is missing for about 37 percent of children in the pool. Socioeconomic characteristics of children with exact and inexact DOB are different. Children with inexact DOB tend to be from families with less educated parents, from rural areas, Muslim, poorer, and shorter in height at all ages.7 Cases in which exact DOB is not known were therefore excluded from the analysis, yielding a subsample of 565,360 children.

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We also excluded children for whom height or exact height measurement date is missing or height-for-age Z-score falls outside of [–6,6] range, which leaves 510,718 children in the sample. Then, we dropped twin births (13,829 cases) due to differences between 4

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The DHS Program conducts nationally representative population and health surveys in developing countries and organizes and publicizes the data. The program is implemented by ICF International and financed by the USAID, the United States Agency for International Development (See: http://dhsprogram.com) 5 Most of the countries are low or lower-middle income, measured by 2015 GNI per capita by the World Bank, countries. The low income countries are Benin, Burkina Faso, Burundi, Central African Republic, Chad, Comoros, Ethiopia, Guinea, Liberia, Malawi, Mali, Mozambique, Niger, Senegal, Sierra Leone, Tanzania, Togo, and Uganda. The lower-middle income countries are Bangladesh, Cameroon, Egypt, Ghana, India, Ivory Coast, Kenya, Kyrgyzstan, Morocco, Nigeria, Pakistan, and Uzbekistan. Seven other countries—Albania, Azerbaijan, Gabon, Jordan, Kazakhstan, Maldives, and Turkey—are among upper-middle income countries (See: https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-andlending-groups). More than 96 percent of observations are from low or lower-middle income countries. 6 An exact DOB includes year, month, and day of birth; an inexact DOB only includes year and month of birth. 7 A controlled examination shows that the likelihood of reporting an exact DOB is correlated with parents’ and household’s socioeconomic characteristics. For example, if mother’s and father’s education increase by one level (education levels are categorized in six groups: no education, incomplete primary, complete primary, incomplete secondary, complete secondary, and higher), then the likelihood of reporting exact DOB increases by about 4.0 and 1.3 percentage points on average, respectively. Also, being Muslim and moving from one wealth quintile to the next quintile down decreases the likelihood of reporting exact DOB by about 3.5 and 2.4 percentage points, respectively. The estimated associations, which are statistically significant, are conditional on holding other covariates constant. The likelihood of reporting exact DOB for a Muslim child is on average about 11.2 percentage point less than that for a non-Muslim child whose parents’ education and wealth are higher by one level. 5

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twin and singleton children’s growth curves. The availability of control variables further restricted the sample: successive additions of constraints on the availability of information on the province or state of residence in the pertinent country, indicators of household wealth, mother’s height, mother’s education and age, father’s education, and father’s age resulted in the exclusion of 1,321, 17,057, 40,263, 4,578, 18,471, and 46,391 children, respectively.8 These constraints decreased the sample size to 368,808 cases. In the last step, we dropped observations for which there are discrepancies between height measurement and interview dates, yielding a final sample size of 308,879 observations.9 Table 1 presents the distribution of observations by mother’s religion and children’s sex.

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Our data refinement process also included computation of children’s height-for-age Zscores. Since different reference populations are used in the computation Z-scores at different phases of DHS, the reported height-for-age Z-scores for children of the same height and age but in different surveys are not always equal. To prevent this type of inconsistency, we re-computed height-for-age Z-scores using a single reference population, World Health Organization (WHO) 2006 Child Growth Standards. The WHO standards are internationally representative and more precise than the formerly used National Center for Health Statistics (NCHS) standards, especially in early infancy.10

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Exposure measures

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2.2.

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We also used information related to household wealth to compute a wealth indicator that is consistent across countries and over time. The information available in all 98 DHS surveys include source of drinking water, type of toilet, main material of the floor, access to electricity, ownership of radio, and ownership of TV. We harmonized contents of these variables across surveys then computed their principle component and used it as a household wealth indicator.

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We also drop children whose mothers’ height falls outside the [120,190] centimeters range to count out outliers and reporting and measurement errors. 9 We use the exact date of measurement of children’s height in the calculation of their height-for-age Z-scores. For about 15 percent of children with reported height, dates of height measurement and interview do not match. In about 80 percent of these cases, measurement date is a date before interview date. These children are on average shorter than those whose measurement and interview dates are identical. The reason for the discrepancy is unclear, but one possibility is that height is transferred from health cards issued before interview. 10 The WHO growth standards are available at: http://www.who.int/nutgrowthdb/en/. The standards are sex-specific in days of age from birth to day 1856, the end of the fourth year of age. 6

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We assumed a normal 270-day gestation length for every child and counted backwards from a child’s exact birth date to determine if the child’s gestation coincided with Ramadan. If gestation did coincide with Ramadan, we then determined the number of days of coincidence (or exposure) during the entirety of the pregnancy, the first, second, and third trimesters, and months one through nine of gestation. After identifying the number of days of exposure to Ramadan, we computed the hours of exposure during the presumed episodes of gestation. Hours of exposure to Ramadan in a specific episode is the summation of hours of exposure in all days of exposure in the episode. Since Ramadan fasting time is in exact accordance with daylight hours, hours of exposure in a Ramadan day are equal to the number of daylight hours in that day. Daylight hours of an exposure day were therefore calculated based on when the day is positioned in the corresponding year and the latitude of the place of residence. We use information on the latitude of place of residence of a household using the Geographical Database, a package provided with most DHSs.11 We label hours of exposure measures as:

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𝐻𝐸𝑅270: hours of exposure to Ramadan during the entirety of gestation

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𝐻𝐸𝑅𝑡𝑗: hours of exposure to Ramadan during trimester j of gestation, j= 1, 2, 3 𝐻𝐸𝑅𝑚𝑘: hours of exposure to Ramadan during month k of gestation, k= 1, 2, …, 9

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Through a set of robustness tests, we also examined other measures of exposure to Ramadan such as days and dummies of exposure. However, we decided to rely on the results from hours of exposure measures in order to account for variations in the exposure to Ramadan by latitude. Hours of exposure, in fact, can vary considerably by latitude. At the northern latitude degree of 40, where Istanbul (Turkey), Baku (Azerbaijan), and Tashkent (Uzbekistan) are approximately located, daylight hours vary by about 5.6 in a year. The difference gradually diminishes moving South. At the equator, where Libreville (Gabon), Kampala (Uganda), and Nairobi (Kenya) are approximately located, the length of a day does not change during the year. In our sample, average daylight hours during Ramadan varies between 9 and 13.

2.3.

Identification strategy and empirical models

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In some surveys, geographical information is not provided. In those cases, we found the pertinent latitude in Google Maps using information on city or town of residence. 7

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To identify the effect of prenatal exposure to Ramadan on children’s height, we used variation in the timing of exposure to Ramadan in utero, not variation in the observance of Ramadan, which is unknown and potentially endogenous. Variation in the exposure to Ramadan is perceived to be exogenous instead. In other words, it is as if the assignment of treatment (i.e., exposure) is random, but the willingness to be treated (i.e., observance) is not random. Therefore, the measured effects present the intent to treat, or reduced form, effects.

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Our identification strategy therefore relied on two assumptions: (1) the exposure to Ramadan in utero is exogenous and (2) the length of gestation is identical for all live births. The summary statistics of children’s and their parents’ observable characteristics provide preliminary evidence on the validity of the first assumption. In Table 2, Panel A, means and standard deviations of the characteristics are presented by children’s sex, their mothers’ religion, and the intensity of exposure. Although there are differences among Muslim and non-Muslim children in terms of their parents’ education and household’s rate of urbanization, the means of the presented characteristics do not change by the intensity of exposure in each group. We further use controlled regressions to examine selection of pregnancy into Ramadan. The results, presented Appendix B, show that overall exposure to Ramadan is not correlated with observables. Trimester results are largely consistent with the overall results; the only exceptions are mother’s and father’s education, which are positively correlated with exposure during the third and first trimesters of gestation, respectively. The correlations imply that the effects of prenatal exposure to Ramadan on height may be underestimated if children of more educated parents are taller.

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We cannot directly examine the validity of the second assumption—that length of gestation is fixed—due to the unavailability of children’s gestation length. In general, Ramadan is considered a moderate nutritional shock that does not change the course of gestation. Almond and Mazumder (2011), for example, use length of gestation information to show that the gestation length may decrease very slightly (by one day) as a result of exposure to Ramadan.

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As a falsification test, we examine the effect of prenatal exposure to Ramadan on nonMuslim children’s height as well. The examination also serves as a test of seasonal effects, which are particularly important in the study of Ramadan since it does not occur at a certain time every solar year, but rather circulates and occurs about 11 days earlier each year such that a full circulation takes 33 years. Hence, seasonal effects can potentially confound the effect of interest. Our large dataset that includes 27 birth years helps to control for seasonal effects effectively. 8

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Means of children’s height-for-age Z-scores reveal signs of the effect of exposure to Ramadan: as the exposure intensifies from none to 30 days, height-for-age Z-score of Muslim male children declines, especially in older children (Table 2, Panel B). However, it is difficult to discern a pattern of effects by intensity of exposure for female children. The identification strategy (illustrated in Fig. 1), reverse J-curves where nonparametric relationships between height-for-age Z-score and months of age were estimated for exposed and non-exposed Muslim male and female children.12 Fig. 1(A) shows that there is no observed difference between height-for-age Z-scores of exposed and nonexposed Muslim male children during the first 24 months, but that difference starts to increase thereafter such that, from about month 44, Muslim male children who were exposed to a full month of Ramadan during the presumed gestation (red line) are consistently shorter in height than Muslim male children who were not exposed (blue line). However, the same analysis for female children (Fig. 1(B)) does not indicate a statistically significant difference in exposed and non-exposed Muslim female children’s height-for-age Z-scores during the 60 months after birth.

(1) (2)

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𝐻𝐸𝐼𝐺𝐻𝑇𝑖 = 𝛼 𝑀 + 𝛽 𝑀 𝐻𝐸𝑅𝑖 + 𝛿 𝑀 𝑋𝑖 + 𝜀𝑖𝑀

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Based on the above-described observation, we specified sex- and age-specific econometric models in which relevant background covariates, which are extensively available in the DHS data, are controlled. We estimated two econometric models for each of the 10 sex-age groups of children—i.e., for 0 to 4 year(s) old male children and 0 to 4 year(s) old female children:

𝐻𝐸𝐼𝐺𝐻𝑇𝑖 = 𝛼 𝑁 + 𝛽 𝑁 𝐻𝐸𝑅𝑖 + 𝛿 𝑁 𝑋𝑖 + 𝜀𝑖𝑁

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where i, M, and N indicate a child, Muslim, and non-Muslim, respectively. Variable HEIGHT is the child’s height-for-age Z-score, and 𝐻𝐸𝑅 is hours of exposure to Ramadan measured by either 𝐻𝐸𝑅270, 𝐻𝐸𝑅𝑡𝑗 (𝑗 is 1 to 3), or 𝐻𝐸𝑅𝑚𝑘 (𝑘 is 1 to 9). All trimester or month exposure measures are included together. Vector X contains control variables, namely the child’s age in days, calendar year of birth, month of birth, birth order, an urban/rural indicator, a full set of country-province fixed-effects, parents’ age at the child’s birth, parents’ education level, mother’s height, and household 12

We estimated Epanechnikov kernel-weighted local polynomial regression of height-for-age Z-score on age in months to obtain the nonparametric relationships. Age in months is computed using the children’s exact birth dates: n is assigned to a child’s months of age if the child is n months and 0–14 days old; n+1 is assigned if the child is n months and 15-30 days old. Partially exposed children are not included. 9

wealth indicator.13,14 In Model 1, only Muslim children are included and the effect of interest is measured by 𝛽 𝑀 . In Model 2, only non-Muslim children are included and the effect is measured by 𝛽 𝑁 . We estimated the models using the ordinary least squares (OLS) method and clustered standard errors at the country level.15

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The described methodology has several, potentially important limitations. There is the possibility of uncontrolled endogeneity. It is also likely that seasonal effects are not fully controlled because, although pooling data from a large number of countries increases the number of birth years then the variation in terms of occurrence of Ramadan, seasonal effects can be country specific. In addition, there is a concern about the increased likelihood of Type I error because of multiple testing. We examine 10 different Muslim subpopulations: 0, 1, 2, 3, and 4 year(s) old male children and 0, 1, 2, 3, and 4 year(s) old female children. Although selection of the subpopulations is based on theory—that growth dynamics are different by sex and age—the large number of groups and tests may lead to unfounded discoveries. That is, even if prenatal exposure to Ramadan has no real effect on height, nominal effects are detected in some subpopulations only due to the multiplicity of tests. We discuss implications of this problem when interpreting the results.

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3. Main results

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The estimated effects of interest, coefficients 𝛽 𝑀 and 𝛽 𝑁 in Models (1) and (2), are multiplied by 12 (the average daylight hours of a typical Ramadan day for exposed children in the sample) and 30 (number of days in the month of Ramadan) and reported in Tables 3 and 4. Each entry in the tables therefore constitutes the average effect on height-for-age Z-score of a full exposure to Ramadan during the corresponding period 13

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Calendar year of birth controls for year-specific effects. It also controls for the general increasing trend in height across nations (Bentham et al., 2016). Month of birth controls for month related effects, vastly documented by researchers (Weber et al., 1998; Costa et al., 2007). Mother’s height controls for genetic effects. Parents’ education levels are included since existing literature shows that their education, especially mother’s, is correlated with children’s height (Behrman and Deolalikar, 1988; Thomas et al., 1991). Finally, the wealth index is included to recognize the well-documented correlation between height and well-being (Case and Paxton, 2008; Mankiw and Weinzierl; 2010). 14 Unlike country and province that are combined to one variable, year and month of birth are included separately to group all January, February, …, and December births. 15 Levels of statistical significance are robust to the choice of clustering level such as country-province, year, year-country, and year-country-province. A multilevel analysis at these levels of clustering provides similar results. 10

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of gestation in a group of children specified by religion, sex, and age. An immediate takeaway from these results is that there are negative associations between exposure to Ramadan and Muslim male children’s height at ages 3 and 4 years. The lack of an observed effect in younger children is consistent with predictions of the fetal origins hypothesis and experimental and semi-experimental findings. Existing research suggests that differential height effect of prenatal nutritional interventions or shocks is usually less pronounced immediately after birth but grows stronger with age (Kusin et al. 1992, Roseboom et al. 2000, Eriksson 2006). Moreover, the likelihood of incorrect measurement is higher in very early childhood (Floud et al., 1990).

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The results also reveal that female children’s height is not negatively associated with prenatal exposure to Ramadan.16 Since the velocity of male and female children’s growth is equal until adolescence, except for the first seven months after birth (Bozzola and Meazza, 2012), we would expect to detect a negative effect on female children’s height by age 4 years. While the possibility of appearance of a negative effect on female children’s height after age 4 years cannot be ruled out, these results could suggest that male children may be more vulnerable to prenatal exposure to Ramadan.17

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As expected, results indicate that controlling for seasonality—using birth year and month—is crucial. When seasonality effects are not controlled, the negative association between exposure to Ramadan during gestation and children’s height at age 4 years, for example, is quite large regardless of sex and religion (Appendix C). After seasonality controls are added, the association can be distinguished from zero only in Muslim male children although its size decreases. Another important confounder is geographic location: controlling for it distinctly changes the size of the association. After all controls are added, variation that determines the size of the effect comes from differences in timing of exposure to Ramadan in children of the same religion, sex, and age. In 4 years old Muslim male children, the association is by about 43 percent smaller in size than the association without any control, but it is still statistically significant.

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Some positive effects on female children’s height at age 1 year are detected. The effects however do not persist to ages 2, 3, and 4 years. Therefore, they do not present a pattern that is consistent with the dynamics of growth in height, which tends to preserve and intensify effects of early life nutritional shocks. 17 Therefore, the results may provide new evidence in support of the fragile male hypothesis (Kraemer 2000). Other studies have shown that in utero exposure to smog, earthquake, severe life events, war, and Ramadan decreases male-to-female birth ratio (Lyster, 1974; Fukuda et al., 1998; Hanson et al., 1999; Zorn et al, 2002; Almond et al., 2011). 11

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While the relative size and statistical significance of the effects on height-for-age Zscore (which are in terms of standard deviations) can be discerned in Tables 3 and 4, converting them to millimeters and graphically illustrating them can be more revealing. Fig. 2 shows ranges of the effect (in millimeters) of exposure during the entirety of gestation in male and female children by religion and age. Fig. 3 shows ranges of the effect of exposure during trimesters of gestation.

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Exposure to a full 30-day Ramadan during the entirety of the presumed gestation is associated with a 3.2 mm decrease in height in 4 years old Muslim male children. For younger Muslim male, Muslim female and non-Muslim children, no significant negative association can be detected (Fig. 2). When trimesters of gestation are considered (Fig. 3), the strongest negative effect appears in 4 years old Muslim male children and amounts to 4.7 mm, coming from trimester 2. Also, exposure during trimester 1 has a significant negative effect on 3 and 4 years old Muslim male children’s height, 3.8 mm and 4.3 mm, respectively.

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A more detailed picture of the effect on height of a 4 years old Muslim male can be seen when exposure during months of gestation is investigated (Fig. 4). The negative height effect amounts to an average 7.3 mm if a full exposure occurs in month 3 of gestation. The effect of exposure during months 4 to 6 are also large and statistically significant.18,19 Depictions of the results of months-of-gestation regressions for 4 years old non-Muslim male children and 4 years old female children, also provided in Fig. 4, show no significant negative effect.20

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Unless the kids in our sample will show differences of larger magnitude later in life, it appears that Ramadan’s effect on height is smaller than the effect of sharper shocks such as famines and floods. For example, Dercon and Porter (2010) find that birth during the peak of the 1984 Ethiopian famine resulted in a 30 mm drop in height in 1725 years old individuals. Examining the effect on height of the 1997-1998 El Nino floods in Ecuador, Rosales (2016), measures 46-60 mm decrease in height in 4-6 years old children who were exposed for the longest period, 3 months. Ramadan effect however is comparable to the effect of early life family income shocks. For example, 18

The figure for 4 years old Muslim male children shows a gradual decrease in the effect from months 3 to 6. Differences between the coefficients however are not statistically significant. Nonetheless, difference between the coefficients and those for the last two months of gestation are, or are close to being, statistically significant. 19 The graph is effectively smoothed since adjacent points are not independent because most Ramadans cover two months. This smoothing applies to lesser extent to Fig. 3 graphs. 20 Results of corresponding regressions are reported in Appendix D. 12

Banerjee et al. (2010) find that birth during the 1863-1890 pest attacks to French vineyards was associated with 6-10 mm decline in height at age 20 years. Maccini and Yang (2009) find that birth during a year with 20 percent more rainfall in rural Indonesia was associated with a 5.7 mm height increase in adult women.

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The gestation episodes during which a significant effect is measured are noteworthy. The critical windows of development of the long bones occur in the first and second trimesters of gestation (Appendix A). These stages of the long bones’ development are complete by the end of month 5 of gestation. By that time, the primary ossification centers in the long bones have formed; they only expand and materialize thereafter. We focus on age 4 years, the age at which a child’s height has a closer resemblance to the child’s ultimate height than that at younger ages.21 Fig. 4 shows that the negative association between exposure to Ramadan and height is large and statistically significant when occurring in months 3-6 of gestation when the long bones’ cartilage models form and develop at the highest rate. The effect however cannot be distinguished from zero in the last three months of gestation.

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Fig. 4 also shows that the association between height and exposure to Ramadan during month 1 of gestation is strong and statistically significant. Months 1 has only a short overlap with a critical window of development of the long bones. The relatively large effects may be attributed to mothers’ higher rate of observance of Ramadan in the first month of pregnancy because of their unawareness to the pregnancy or the lower burden of fasting.22

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The results discussed in this section cannot be used to draw firm conclusions about the effect on height of prenatal exposure to Ramadan due to the possibility of identifying false effects because of multiple comparisons. Out of 10 entirety-of-gestation tests on Muslim children, one shows a negative association between prenatal exposure to Ramadan and height. Also, out of 10 trimesters-of-gestation tests, two show negative associations. This finding alongside the possibilities of unaddressed heterogeneity and imperfectly controlled seasonality implies that chance, not a causal force, may also be the driver of the effects. Therefore, follow-up studies that examine older than 4 years 21

The correlation between a newborn’s length and his/her adulthood height is about 25 to 30 percent (Schmidt et al., 1995). The correlation rapidly increases to about 60 and 70 percent by age 2 years for girls and boys, respectively. By age 4 years, the correlation increases at a slower pace to about 70 and 80 percent for girls and boys, respectively (Cole and Wright, 2011). 22 There is a possibility that the effect of exposure during first month of pregnancy is confounded by religious adherence. In addition to eating and drinking, those who fast are required to abstain from sextual activities during the daytime. If abstaining from sexual activities affects the number of conception during Ramadan, then women who become pregnant during Ramadan may be atypical. 13

old children and benefits from statistical power are needed to validate the effects observed here.

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The results however are very suggestive because of who (male children) and when (older children) the height effects appear to match with findings of the existing height literature. Also, the episodes of gestation during which exposure to Ramadan has a significant effect on height largely overlap with the critical windows of development of a fetus’ long bones. Furthermore, levels of statistical significance of the associations are very high for 4 years old Muslim male children. In addition, the associations persist through a series of robustness tests in which observations from overrepresented countries are dropped, digit preference in reporting the day of birth is considered, alternative measures of exposure are examined, an alternative method of calculating height-for-age Z-scores is employed, children with inexact DOB are added to the sample, and surveys in which a significant number of children lack the exact DOB are dropped (Appendix E). Appendix E also provides a discussion on the effect of including exposure during pre-conception months into the regressions and on the data limitations.

4. Variation in the effect by region

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We pool data from a large number of countries in this study, thus imposing substantial cultural, institutional, and geographical heterogeneities to the sample. While the exclusion of specific countries from the sample does not change the pattern of the effects, the sizes of the effects moderately change (Appendix E). We cannot conduct credible country-specific analyses since surveys from specific countries do not cover enough birth years to reasonably control for seasonal effects. Instead, we grouped the countries with cultural and geographical similarities into regions in the dataset and measured the heterogeneity in the effect. In practice, we grouped the countries into four regions: West Africa, East and Central Africa, Middle East and North Africa, and South and Central Asia (WAF, ECAF, MENA, and SCAS, respectively, hereafter).23

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West African countries are Benin, Burkina Faso, Cameroon, Gabon, Ghana, Guinea, Liberia, Ivory Coast, Mali, Nigeria, Senegal, Sierra Leone, and Togo. East and Central African countries are Burundi, Central African Republic, Chad, Comoros, Ethiopia, Kenya, Malawi, Mozambique, Niger, Tanzania, and Uganda. Middle East and North African countries are Albania, Azerbaijan, Egypt, Jordan, Morocco, and Turkey. South and Central Asian countries are Bangladesh, India, Kazakhstan, Kyrgyzstan, Maldives, Pakistan, and Uzbekistan. 14

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In the sample of children from each region, at least 22 continuous birth years and a sizable number of Muslims and non-Muslims are present. Regional estimations of the effects on Muslim children’s height-for-age Z-score, by sex and age, are presented in Appendix F. The region-specific effects are largely similar to the original effects: in most regions, the entirety-of-gestation regressions show that there is a negative association between exposure to Ramadan and height in 4 years old Muslim male children; the trimester regressions show strong negative associations of exposure during early trimesters, especially in 4 years old Muslim male children.

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Fig. 5 illustrates the region-specific effects on height (in mm) for 4 years old Muslim male children. Exposure during gestation, regardless of its timing, has statistically significant association with children’s height in two regions, WAF and SCAS. Also, only these two regions reveal a negative, statistically significant association between exposure during the first two trimesters and height. In ECAF, no negative association is detected. In MENA, only exposure during the last trimester of gestation and children’s height is statistically significant. The largest effect is that of exposure during the mid-gestation trimester in SCAS (on average about -9.1 mm), which is mainly driven by Bangladesh.

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We tested if region-specific differences in effects on 4 years old Muslim children are statistically significant (Appendix F). When the entirety of gestation is considered, the differences between the effect in ECAF and other regions are statistically significant. However, the differences between the effects in WAF, MENA, and SCAS are not statistically significant. In the trimester regressions, the differences between the effect in ECAF and other regions again are, or are close to being, statistically significant. The difference of none of the trimesterly effects between WAF and SCAS can be distinguished from zero. However, when trimesterly effects in WAF and SCAS are compared to those in MENA, significant differences are observed. Specifically, in both WAF and SCAS, the effect of exposure on height during trimester 2 is greater than that in MENA; on the other hand, the effect on height of exposure during trimester 3 is greater in MENA than that in WAF and SCAS.

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The between-region differences in the effect must be interpreted with caution. First, strong between-region differences could be attributable in part to the reduced sample size. Also, limiting the study to a region decreases the number of birth years and, thus rendering the effect prone to seasonal influences. Therefore, our region-specific results are merely suggestive of the need for further investigation into possible variation associated with geographic location.

5. Variation in the effect by religiosity 15

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A key unobservable variable in this study is observance of Ramadan by Muslim pregnant women. Although they are exempted from fasting, numerous surveys show that fasting is prevalent among them (Arab and Nasrollahi, 2001; Makki, 2002; Joosoph et al., 2004; Mubeen et al., 2012; van Bilsen et al., 2016). In this section, we conduct tests that are designed to measure the effects on height of exposure to Ramadan by the perceived or revealed degree of religiosity in the countries.

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In the first test, we measure the effects in majority and minority Muslim countries, presuming that a larger percentage of Muslims in the population is associated with a higher degree of adherence to Ramadan.24 We extract the percentage of Muslim population in 2010 in the 37 countries from a PEW Research Center report and estimate sex- and age-specific effects of prenatal exposure to Ramadan on Muslim children’s height in countries where Muslims constitute more and less than 50 percent of population (PEW, 2012a). In countries where Muslims constitute more than 50 percent of population, the results are similar to the original results: strong negative effects appear in Muslim male children, especially at age 4 years, but there is no effect in female children (Appendix G). In countries where Muslims constitute less than 50 percent of population, none of the effects can be distinguished from zero. In Fig. 6, the effects on 4 years old Muslim male children’s height in the two groups of countries are combined, showing statistically significant negative associations of exposure during the entirety and the first two trimesters of gestation on height in Muslim majority countries. Our between-group examinations show that differences of the effects of exposure during the entirety and the first and third trimesters of gestation are statistically significant (Appendix G).

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In the second test, we use the results of a 2009 Gallup poll in which respondents from 114 countries, including the countries of our study, were asked if religion is important in their daily lives (Crabtree, 2010).25 Since the percentage of respondents who answered “yes” to this question is very high in most countries, we used a 95 percent 24

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Using results of The Global Islam surveys by PEW Research Center, we cannot demonstrate a strong correlation between share of Muslim population and degree of commitment to Islam (PEW, 2012a,b). However, the influence of population on likelihood of fasting by pregnant Muslim women may not be completely ruled out since microdata analyses have documented a strong association between size of religious network and religiosity (Cornwall, 1989). In a more recent study, Stroope (2012)—examining the effect of social embeddedness of religion on a set of religious beliefs and activities—finds that the number of a person’s friends who attend the person’s place of worship is strongly correlated with having fervent religious beliefs and participation in religious activities. Findings of the literature is relevant to our study if size of a religious network is positively correlated with the religious population. 25 Muslims were not separated from non-Muslims in the poll. 16

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threshold to form two groups of countries: countries in which more and less than 95 percent of respondents answered “yes” to the question (Appendix G). In 4 years old Muslim male children, the associations between exposure during the entirety and the first two trimesters of gestation are statistically significant in countries in which religion is important in daily lives of 95 percent or more of population (Fig. 6). Our crossgroup examinations show that differences in the effects of exposure during the entirety and the first trimester of gestation are statistically significant (Appendix G).

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In the last test, we used the results of another PEW Research Center poll in which several questions are asked about Muslims’ religious commitment (PEW, 2012b). Our question of interest asks about observing Ramadan, although sex and pregnancy status of respondents is not reported. We keep countries that are included in the PEW study and divide them to two groups: countries in which more and less than 90 percent of respondents answered yes to the question (Appendix G). Interestingly, the strongest adverse effects on height of exposure to Ramadan appear in this test, which uses data more relevant to the context of Ramadan than the other measures of religiosity (Appendix G and Fig. 6). Our cross-group examinations show that differences of the effects of exposure during the entirety and the second trimester of gestation are statistically significant in 4 years old Muslim male children (Fig. 6).

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The above-described tests suggest that the degree of perceived and revealed religiosity, as well as reported observation of Ramadan, may have an influence on the magnitude of the effect on height of prenatal exposure to Ramadan. The results of each test are robust to decreasing the thresholds of categorization by 5 percent. Further lowering of the thresholds reduces the number of observations in each sex-age group also the number of birth years so dramatically that the tests are no longer statistically credible.

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6. Policy implications and conclusion

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Birthweight is usually used as the barometer of nutritional environment in utero and as the leading predictor of long-term health (Currie and Moretti, 2007; Currie, 2009). We however measure significant negative association between Muslim male children’s height at age 4 years and exposure to Ramadan during mid- and early-gestation episodes. In fact, an inflicted change in phenotype, if any, need not to be immediately visible at birth (Kusin et al., 1992; Roseboom et al., 2000; Eriksson, 2006). Even when the effect at birth is identifiable in birthweight, the conveyed information is not necessarily the same as what can be disclosed by height since birthweight is mostly affected by 17

nutritional environment during the late gestation months, whereas height is more sensitive to nutrition during early and mid-gestation months, when most vital organs form.

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Unlike human and natural disasters, which are exogenous to individual choices and are often unpredictable, Ramadan’s effect originates from people’s individual decisions. Therefore, the effects can be avoided, especially because pregnant women are exempted from fasting in Islam. The leading reasons for fasting of pregnant Muslim women are unawareness of harms of fasting during pregnancy, unawareness of their exemption, and reluctance to make up for it after pregnancy (Abd-El-Aal et al. 2009; van Bilsen et al. 2016). Advocating for the provision of information to Muslim women about the possible harms of fasting during pregnancy and the complete and unequivocal exemption of pregnant from fasting by religious authorities and improving workplace nutritional environment for pregnant women by, for example, assigning designated areas for their eating during Ramadan are some policies that could be pursued to reduce harm to Muslim children.

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Acknowledgements

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Finally, we acknowledge that the results of this study are suggestive, especially because the effect on height appears only in the oldest children in the sample, i.e., the 4 years old. In particular, whether the effect on height of prenatal exposure to Ramadan is detected in older children and adults, and if it amplifies by age, is left to complementary studies that use precise anthropometric information. Such information is not available in the data we use, but it is an important line on inquiry that needs to be pursued.

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We are especially grateful to Richard Akresh, Dan Bernhardt, German Caruso, Firouz Gahvari, Chunling Lu, Sarah Miller, and Salim Rashid for their extensive comments and suggestions. We are indebted to two anonymous reviewers of an earlier paper (titled “pre-birth exposure to Ramadan, height, and the length of gestation) for their insightful comments and providing guidance for new investigations that led in this paper. We are also grateful for comments from seminar participants at the University of Illinois at Urbana-Champaign, the Fourth Conference on Long-Run Impacts of Early Life Events at the University of Michigan, the Truman State University, Lancaster University, University of Washington, ERF’s 23rd Annual Conference, and the MENA Chief Economist Seminar Series in the World Bank. We also appreciate insightful discussions with Hossein A. Abbasi, Linda Adair, Katie Baird, Kristine Brown, Meltem Dayioglu, George Deltas, Keyvan Eslami, Juan Fung, Jamal Ibrahim Haidar, Yashar Heydari Barardehi, Cynthia Howson, Diana Kuh, Kara Luckey, Bhashkar Mazumder, William McGuire, David Molitor, Rafael Ribas, Ken Smith, and Reyn van Ewijk. The views, findings, and conclusions expressed in this paper however are those of the authors alone.

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Fig. 1(A): Height-for-age Z-score versus months of age by exposure to Ramadan (Muslim male children)

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Fig. 1(B): Height-for-age Z-score versus months of age by exposure to Ramadan (Muslim female children)

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Notes: The figures show the kernel-weighted local polynomial regressions (using Epanechnikov kernel) of height-for-age Z-score on months of age. The exposed children in the regressions are those who were exposed to a full month of Ramadan in utero. Data Source: Demographic and health surveys, the DHS Program, USAID.

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Fig. 2(A): The e_ect on height (in millimeters) of a full 30-day exposure to Ramadan during the entirety of gestation in male children by age

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Fig. 2(B): The e_ect on height (in millimeters) of a full 30-day exposure to Ramadan during the entirety of gestation in female children by age

Notes: The figures present sex- and age-specific ranges of the effect on height of a full-30 day exposures to Ramadan during the presumed gestation period when exposed and non-exposed Muslim children are compared. Each range is shown by a vertical line for which the 25

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corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficient, inserted in column “Muslim” in Table 3, is multiplied by 360 (=12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals.

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Fig. 3(A): The e_ect on height (in millimeters) of a full 30-day exposure to Ramadan during the trimesters of gestation in male children by age

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CC

EP

Notes: The figures present religion- and age-specific ranges of the effect on height of a full-30 day exposures to Ramadan during the presumed trimesters of gestation when exposed and nonexposed Muslim male children are compared. Each range is shown by a vertical line for which the corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficient, inserted in column “Muslim” in Table 4, is multiplied by 360 (= 12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals.

27

EP

TE

D

M

A

N

U

SC RI PT

Fig. 3(B): The e_ect on height (in millimeters) of a full 30-day exposure to Ramadan during the trimesters of gestation in female children by age Notes:

A

CC

Notes: The figures present religion- and age-specific ranges of the effect on height of a full-30 day exposures to Ramadan during the presumed trimesters of gestation when exposed and nonexposed Muslim female children are compared. Each range is shown by a vertical line for which the corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficient, inserted in column “Muslim” in Table 4, is multiplied by 360 (= 12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals.

28

Fig. 4(A): The e_ect of a full 30-day exposure to Ramadan during months of gestation on 4 years old Muslim male children's height (in millimeters)

EP

TE

D

M

A

N

U

SC RI PT

Fig. 4(B): The e_ect of a full 30-day exposure to Ramadan during months of gestation on 4 years old Muslim female children's height (in millimeters)

A

CC

Notes: The figure presents within-Muslim ranges of the effect on height of a full-30 day exposures to Ramadan during the presumed months of gestation in 4 years old male children. Each range is shown by a vertical line for which the corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficient, provided in Appendix B Table B10, is multiplied by 360 (= 12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals.

29

A

N

U

SC RI PT

Fig. 5: The e_ect of a full 30-day exposure to Ramadan during episodes of gestation on 4 years old Muslim males children's height (in millimeters) by region

A

CC

EP

TE

D

M

Notes: The figure presents overall and region-specific within-Muslim ranges of the effect on height of a full-30 day exposures to Ramadan during the entirety and trimesters of the presumed gestation in 4 years old male children. Each range is shown by a vertical line for which the corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficients are multiplied by 360 (= 12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals. West Africa includes Benin, Burkina Faso, Cameroon, Gabon, Ghana, Guinea, Ivory Coast, Liberia, Mali, Nigeria, Senegal, Sierra Leone, and Togo. East and Central Africa includes Burundi, Central African Republic, Chad, Comoros, Ethiopia, Kenya, Malawi, Mozambique, Niger, Tanzania, and Uganda. Middle East and North Africa includes Albania, Azerbaijan, Egypt, Jordan, Morocco, and Turkey. South and Central Asia includes Bangladesh, India, Kazakhstan, Kyrgyzstan, Maldives, Pakistan, and Uzbekistan.

30

Fig. 6(A): The e_ect of a full 30-day exposure to Ramadan during episodes of gestation on 4 years old Muslim male children's height (in millimeters) in groups of countries with higher degree of religiosity conjectured from the share of Muslim population, revealed importance of religion in daily life, and revealed observance of Ramadan

D

M

A

N

U

SC RI PT

Fig. 6(B): The e_ect of a full 30-day exposure to Ramadan during episodes of gestation on 4 years old Muslim male children's height (in millimeters) in groups of countries with lower degree of religiosity conjectured from the share of Muslim population, revealed importance of religion in daily life, and revealed observance of Ramadan

A

CC

EP

TE

Notes: The figure presents overall and group-specific within-Muslim ranges of the effect on height of a full-30 day exposures to Ramadan during the entirety and trimesters of the presumed gestation in 4 years old male children. Each range is shown by a vertical line for which the corresponding average effect is at the middle (marked by a bold horizontal line) and the corresponding 95% confidence interval is shown at both ends. To find the range of the effects, the corresponding estimated coefficients are multiplied by 360 (= 12 × 30) because an exposed child in the sample experienced Ramadan days that were about 12 hours long on average. The resulted number is the effect of a full 30-day exposure to Ramadan during the episode on the child's height-for-age Z-score. Then, the latter number, multiplied by the corresponding standard deviation in the reference population, gives the effect in millimeters. The same calculation is repeated for the upper and lower bounds of the 95% confidence intervals. Countries with more than 50\% Muslim population are Albania, Azerbaijan, Bangladesh, Burkina Faso, Chad, Comoros, Egypt, Guinea, Jordan, Kazakhstan, Kyrgyzstan, Mali, Morocco, Niger, Pakistan, Senegal, Turkey, Uzbekistan, Maldives, Sierra Leone (according to PEW 2012). Countries in which more than 95% believed religion is important in daily life are Bangladesh, Burundi, Cameroon, Comoros, Egypt, Ethiopia, Guinea, Jordan, Malawi, Morocco, Niger, Nigeria, and Senegal (according to Gallup 2009). Countries in which more than 90% said they observe Ramadan are Bangladesh, Cameroon, Chad, Egypt, Ethiopia, Ghana, Kenya, Mali, Morocco, Niger, Nigeria, Pakistan, Senegal, Tanzania (according to PEW 2012).

31

SC RI PT

Table 1: Surveying years and number of children by country, religion and sex in the regression sample

11 Egypt 12 Ethiopia 13 Gabon Guinea India Ivory Coast Jordan Kazakhstan Kenya Kyrgyzstan Liberia Malawi Maldives Mali

A

CC

15 16 17 18 19 20 21 22 23 24 25

1996-97 , 2004 1996 , 2012 1995-96 , 2005 , 2008 , 2014 1992 , 1997 , 2003 2000 , 2012 1998-99 , 2003 , 2008 , 2014 1999 , 2005 , 2012 1998-99 , 2005-06 2011-12 1997 , 2012 1995 1998 , 2003 , 2008-09 1997 2006-07 , 2013 2000 , 2004-05 , 2010 2009 1995-96 , 2001 , 2006 2012-2013 2003-04 1997 , 2003-04 , 2011

EP

14 Ghana

1994-95

26 Morocco 27 Mozambique

NonMuslims Boys Girls 87 81 2 3 1,036 980

U

975 937 3,005 2,899 46 42 614 586

N

Benin Burkina Faso Burundi Cameroon Central Afr. 8 Rep. 9 Chad 10 Comoros

Boys Girls 420 445 962 831 9,580 9,137

87

M

4 5 6 7

2008-2009 2006 1996-97 , 1999-2000 2004 , 2007 , 2011 1996 , 2006 , 2011-2012 1998-99 , 2003 , 2010 2010-2011 1998 , 2004 , 2011

D

Albania Azerbaijan Bangladesh

TE

1 2 3

Survey Years

A

Country

Muslims

94

1,596 1,716 963 953 ###

###

2,704 2,485 151 120

Percentage in Total 0.3 0.6 6.7

4,362 2,031 1,171 2,205

4,432 2,013 1,108 2,249

3.5 3.2 0.8 1.8

776

753

0.6

1,174 1,110 3 6 848

741

1.8 0.6 12.3

4,380 4,248 1,657 1,655

4.5 1.2

513

443

2,515 2,438

1.9

1,974 2,688 267 5,629 229 603 426 316 1,180 476 8,297

1,835 2,484 262 5,275 257 511 407 250 1,217 513 8,143

247 208 ### ### 253 272 36 49 81 94 3,793 3,808 38 24 2,042 1,887 6,895 6,960 0 0 705 700

1.4 12.5 0.3 3.6 0.2 2.8 0.3 1.5 5.3 0.3 5.8

2,286 2,213 955 1,010

0 0 4,868 4,940

1.5 3.8

32

Niger Nigeria Pakistan Senegal Sierra Leone Tanzania Togo Turkey Uganda Uzbekistan Total

1998 , 2006 , 2012 1999 , 2003 , 2008 , 2013 2012-13 2005 , 2010-11 2008 , 2013 1996 , 2004-05 1998 , 2013-14 1998 2000-01 , 2006 , 2011 1996 83 surveys

2,583 7,883 924 1,510 1,565 1,783 418 1,034 404 486 ###

2,402 8,022 911 1,361 1,646 1,713 397 860 390 464 ###

8 6,267 0 47 365 2,889 1,993 3 2,618 11 ###

14 6,023 0 56 377 2,860 2,031 5 2,636 14 ###

A

CC

EP

TE

D

M

A

N

U

Data Source: Demographic and health surveys, the DHS Program, USAID.

33

1.6 9.1 0.6 1.0 1.3 3.0 1.6 0.6 2.0 0.3 100

SC RI PT

28 29 30 31 32 33 34 35 36 37

Table 2: Summary statistics of children's and their parents' characteristics and children's height-for-age Z-Scores Muslims

Non-Muslims

3.39 (2.34)

(2.34) Mother's Education (Years)

Father's Education (Years)

Mother's Age at Birth

Father's Age at Birth

M 158

(6.77)

D

(6.80) Urban (%)

36 25,805

TE

Obs.

(4.89) 26.59

36

27,179

Partially Exposed 3.39

Fully Exposed

3.39

(2.29) 4.55

(4.52) 6.29

(4.87)

26.65

(6.43)

(2.29) 4.52

(4.48) 6.26

(4.83) 26.56

(6.38)

35.51

33.59

(9.84)

(9.40)

158

156

(6.75)

(6.82)

35 112,272

28 22,632

23,835

28 97,156

-0.67

-0.77

-0.80

-0.84

(2.00)

(1.86)

-1.60

-1.79

(1.93)

(1.80)

-1.75

-1.94

(1.85)

(1.63)

-1.60

-1.85

(1.76)

(1.52)

-1.46

-1.66

A

(9.82)

(9.69) 158

(6.47)

35.52

35.52

Mother's Height (cm)

26.60

(6.42)

(6.46)

6.28

(5.55)

26.56

26.66

(4.50)

5.29

(5.50)

(5.54)

4.54

(5.12)

5.28

5.40

(2.27)

4.32

(5.07)

(5.14)

3.37

(2.35)

4.35

4.42

3.42

U

3.41

Not Exposed

N

Birth Order

Fully Exposed

SC RI PT

Not Partially Variables Exposed Exposed Panel A: Parents' and Household's Characteristics

33.63 (9.45) 156 (6.87) 28

(6.38) 33.67 (9.46) 157 (6.84)

Panel B: Height-for-Age Z-Scores by Age

EP

Height-for-Age Z-Score at Age 0

CC

Height-for-Age Z-Score at Age 1

A

Height-for-Age Z-Score at Age 2 Height-for-Age Z-Score at Age 3 Height-for-Age Z-Score at Age 4

-0.68 (1.99) -1.65 (1.92) -1.71 (1.83) -1.48 (1.70) -1.33

Boys: -0.67 (1.98) -1.62 (1.94) -1.75 (1.90) -1.50 (1.72) -1.38

34

(1.88) -1.84 (1.82) -2.02 (1.65) -1.83 (1.54) -1.68

(1.92) -1.94 (1.76) -2.02 (1.65) -1.90 (1.59) -1.74

(1.64) 13,227

Obs.

(1.61)

(1.63) 57,331

13,706

(1.50)

(1.42) 11,617

12,169

(1.50) 49,336

-0.46

-0.58

-0.59

-0.64

(1.89)

(1.86)

Girls:

(1.85)

Height-for-Age Z-Score at Age 1

-1.42

-1.39 (1.89)

(1.93) Height-for-Age Z-Score at Age 2

-1.63

-1.54

Height-for-Age Z-Score at Age 4

-1.38 (1.67) 12,578

-1.40

(1.55)

-1.58

(1.77)

(1.74)

-1.33

-1.43

(1.65) 13,473

-1.77

(1.86)

(1.61) 54,941

M

Obs.

(1.74)

-1.60

(1.75)

(1.70)

-1.57

(1.92)

-1.66

(1.83) Height-for-Age Z-Score at Age 3

-1.35

-1.72

(1.53)

U

(1.93)

(1.78)

(1.82)

SC RI PT

-0.50

N

-0.57

A

Height-for-Age Z-Score at Age 0

-1.71

(1.45) 11,015

-1.59

(1.69)

-1.80

(1.62)

-1.76

(1.50)

-1.72 (1.44) 11,666

-1.70

(1.70) -1.89

(1.61) -1.84

(1.59) -1.74

(1.47) 47,820

A

CC

EP

TE

D

Notes: A partially exposed child is a child who was exposed to Ramadan for 1 to 29 days during the presumed 270-day period of gestation, but a fully exposed child is exposed to a full 30-day Ramadan during the period. Standard deviations are in parentheses. Height-for-age Z-score are calculated using the WHO 2006 reference population. Data Source: Demographic and health surveys, the DHS Program, USAID.

35

Table 3: The effect of a full 30-day exposure to Ramadan during the entirety of gestation on height-for-age Z-score by sex, religion and age of

Girls Non-

Non-

Muslims

Muslims

Muslims

Muslims

exposure270

0.004

0.052

0.080

0.041

(0.040) [0.927]

(0.040) [0.206]

(0.055) [0.16]

(0.039) [0.304]

Obs.

19,975

18,385

19,274

17,979

exposure270

0.005

-0.021

0.077**

-0.040

(0.031) [0.874]

(0.037) [0.571]

(0.036) [0.039]

(0.030) [0.2]

Obs.

18,027

16,921

17,285

16,322

exposure270

-0.019

0.002

0.049

-0.011

(0.033) [0.573]

(0.025) [0.93]

(0.033) [0.154]

(0.035) [0.761]

Obs.

16,845

15,431

16,257

exposure270

-0.026

0.035

-0.007

(0.042) [0.546]

(0.045) [0.436]

15,347

3 Obs. exposure270 4

N 14,924

(0.034) [0.851]

(0.056) [0.409]

11,735

14,835

11,173

0.021

0.019

0.007

-0.073***

-0.047

(0.020) [0.001]

(0.036) [0.576]

(0.037) [0.613]

(0.029) [0.81]

14,070

10,650

13,341

10,103

EP

Obs.

A

2

M

1

D

0

U

Exposure

TE

Age

Boys

SC RI PT

Measure

A

CC

Notes: exposure270 indicates a full 30-day exposure to Ramadan during the presumed 270-day period (entirety) of gestation. The corresponding effects are found by multiplying estimations of the coefficient of HER270 (hours of exposure during the entirety of gestation) in the Models (1) or (2) by 360 (= 12 × 30, 12 is average daylight hours in a Ramadan day in the sample and 30 is the number of days). There is a separate regression for each subgroup of children specified by sex, mother's religion, and age. Control variables in all regressions are children's age in days, children's year, month, and order of birth, an urban/rural indicator, a variable that indicates country and province of residence, parents’ age at children's birth, parents' education, mothers' height, and households' wealth indicator. Obs. is the abbreviation for number of observations. Standard errors, presented in parentheses, are clustered at country level. P-values are presented in brackets and used to show the statistical significance levels at the 1, 5, and 10 percent are indicated by ***, **, and *, respectively. Data Source: Demographic and health surveys, the DHS Program, USAID. 36

Table 4: The effect of a full 30-day exposure to Ramadan during trimesters of gestation on height-for-age Z-score by sex, religion and age of

Girls Non-

Non-

Muslims

Muslims

Muslims

Muslims

exposureT1

0.018

0.089**

0.147*

0.053

(0.053) [0.728]

(0.035) [0.017]

(0.077) [0.062]

(0.041) [0.208]

-0.008

0.016

0.05436

0.059

(0.053) [0.879]

(0.046) [0.727]

(0.042) [0.201]

(0.047) [0.219]

0.000

0.040

0.044

0.019

(0.050) [0.995]

(0.062) [0.525]

(0.069) [0.528]

(0.049) [0.705]

Obs.

19,975

18,385

19,274

exposureT1

0.022

-0.025

0.063

(0.039) [0.582]

(0.036) [0.502]

-0.017

17,979 -0.046

(0.030) [0.137]

0.008

0.106**

0.003

(0.049) [0.877]

(0.048) [0.032]

(0.052) [0.957]

-0.036

0.064

-0.060

(0.039) [0.832]

(0.051) [0.492]

(0.047) [0.179]

(0.043) [0.173]

18,027

16,921

17,285

16,322

-0.025

-0.002

0.042

-0.017

(0.040) [0.542]

(0.028) [0.937]

(0.036) [0.245]

(0.031) [0.582]

exposureT2

-0.032

0.019

0.05112

0.008

(0.043) [0.461]

(0.046) [0.687]

(0.047) [0.281]

(0.057) [0.893]

-0.001

-0.004

0.052

-0.016

(0.048) [0.976]

(0.033) [0.912]

(0.047) [0.273]

(0.051) [0.753]

exposureT2

0.008

EP

exposureT3

TE

(0.045) [0.712]

1

Obs.

A

exposureT1

2

exposureT3

D

(0.044) [0.162]

CC

exposureT3

N

0

A

exposureT2

U

Exposure

M

Age

Boys

37

SC RI PT

Measure

15,431

16,257

14,924

exposureT1

-0.095*

0.020

-0.033

-0.075

(0.052) [0.078]

(0.054) [0.715]

(0.049) [0.503]

(0.047) [0.119]

0.034

0.023

0.007956

-0.047

(0.049) [0.493]

(0.068) [0.738]

(0.048) [0.868]

(0.074) [0.527]

-0.009

0.055

0.008

-0.017

(0.047) [0.85]

(0.047) [0.247]

(0.032) [0.813]

(0.074) [0.822]

15,347

11,735

14,835

11,173

-0.098***

-0.009

0.005

0.016

(0.035) [0.009]

(0.056) [0.881]

(0.035) [0.88]

(0.043) [0.715]

-0.107***

0.053

0.016632

0.006

(0.028) [0.001]

(0.050) [0.301]

(0.036) [0.647]

-0.025

0.038

0.033

(0.032) [0.433]

(0.051) [0.46]

14,070

10,650

exposureT1

exposureT2 4 exposureT3

Obs.

N

Obs.

(0.039) [0.886]

A

exposureT3

M

3

D

exposureT2

SC RI PT

16,845

U

Obs.

-0.001

(0.062) [0.597]

(0.042) [0.973]

13,341

10,103

A

CC

EP

TE

Notes: exposureT1, exposureT2, and exposureT3 indicate full 30-day exposure to Ramadan during trimesters 1, 2, and 3 of gestation, respectively. The corresponding effects are found by multiplying estimations of coefficients of HERt1, HERt2, and HERt3 (hours of exposure during trimesters 1, 2, and 3, respectively) in the Models (1) or (2) by 360 (= 12 × 30, 12 is average daylight hours in a Ramadan day in the sample and 30 is the number of days). There is a separate regression for each subgroup of children specified by sex, mother's religion, and age. Control variables in all regressions are children's age in days, children's year, month, and order of birth, an urban/rural indicator, a variable that indicates country and province of residence, parents' age at children's birth, parents' education, mothers' height, and households' wealth indicator. Obs. is the abbreviation for number of observations. Standard errors, presented in parentheses, are clustered at country level. P-values are presented in brackets and used to show the statistical significance levels at the 1, 5, and 10 percent are indicated by ***, **, and *, respectively. Data Source: Demographic and health surveys, the DHS Program, USAID.

38