Characterizing gestational weight gain in a cohort of Indigenous Australian women

Author’s Accepted Manuscript Characterizing gestational weight gain in a cohort of Indigenous Australian women Tracy L. Schumacher, Loretta Weatherall, Lyniece Keogh, Kathryn Sutherland, Clare E. Collins, Kirsty G. Pringle, Kym M. Rae www.elsevier.com/locate/midw

PII: DOI: Reference:

S0266-6138(18)30021-4 https://doi.org/10.1016/j.midw.2018.01.017 YMIDW2183

To appear in: Midwifery Received date: 10 December 2017 Accepted date: 26 January 2018 Cite this article as: Tracy L. Schumacher, Loretta Weatherall, Lyniece Keogh, Kathryn Sutherland, Clare E. Collins, Kirsty G. Pringle and Kym M. Rae, Characterizing gestational weight gain in a cohort of Indigenous Australian women, Midwifery, https://doi.org/10.1016/j.midw.2018.01.017 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 galley proof before it is published in its final citable 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.

Characterizing gestational weight gain in a cohort of Indigenous Australian women Tracy L. Schumacher PhD (Dr)1,2,3,4, Loretta Weatherall , Indigenous Research Coordinator1,2, Lyniece Keogh Executive Officer1,2, Kathryn Sutherland Aboriginal Primary Health Care Trainee1,2, Clare E. Collins PhD Professor, NHMRC Senior Research Fellow3,4, Kirsty G. Pringle PhD ARC Future Fellow5,6, Kym M. Rae PhD Associate Professor1,2,6,7,8*

1

Gomeroi gaayngal Centre, Faculty of Health and Medicine, University of Newcastle, 2/1 Hinkler Rd, Tamworth NSW 2340, Australia (Twitter:@GomeroiBabies) 2

School of Medicine and Public Health, Faculty of Health and Medicine, University of Newcastle, University Drive, Callaghan NSW 2308, Australia 3

Priority Research Centre for Physical Activity and Nutrition, University of Newcastle, Ring Rd, Callaghan NSW 2308, Australia 4

School of Health Sciences, Faculty of Health and Medicine, University of Newcastle, University Drive 5

School of Biomedical Sciences and Pharmacy, University of Newcastle, University Drive, Callaghan NSW 2308, Australia 6

Priority Research Centre of Reproductive Sciences, University of Newcastle, University Drive, Callaghan NSW 2308, Australia 7

Priority Research Centre of Generational Health and Ageing, University of Newcastle, University Drive, Callaghan NSW 2308, Australia 8

Department of Rural Health, University of Newcastle, Tamworth, NSW, 2340, Australia

[email protected] Twitter: @DrTSchumacher [email protected] [email protected] [email protected] [email protected] Twitter: @ProfCCollins [email protected] Twitter: @Dr_Kirsty_Pringle [email protected]

Twitter: @Kym_M_Rae Abstract Objective to determine the adequacy of gestational weight gain for a cohort of Indigenous Australian women and investigate whether it is associated with pre-pregnancy body mass index. Design analysis of observational data collected from a longitudinal cohort study that follows Indigenous Australian women through pregnancy. Setting women recruited through antenatal clinics in a regional and remote town in NSW, Australia to the Gomeroi gaaynggal program. Participants 110 pregnant women who either identify as being an Indigenous Australian or as carrying an Indigenous child. Measurements and findings measurements included weight and height, selfreported pre-pregnancy weight and smoking status, parity and health conditions that may contribute to gestational weight gain, such as hypertensive or diabetic disorders. Compared to the 2009 Institute of Medicine recommendations for gestational weight gain and based on prepregnancy body mass index, the rate of adequate gestational weight gain in this cohort was very low (15%). 32% of women had inadequate weight gain and 54% had excessive weight gain. The highest rate of excessive gestational weight gain was found in overweight women (74%), with rates of 48% and 50% found in healthy and obese (all classes) categories, respectively. Parity (coefficient 4.5, p<0.01) and hypertension (coefficient 4.8, p=0.04) were found to be significantly associated with gestational weight gain in mixed model linear regression. Conclusions Few women gained adequate gestational weight. Culturally acceptable ways of addressing this issue are needed for this group of women, as inadequate and excessive rates of gestational weight gain have health implications for women and their offspring. Implications for Practice: a systematic approach to addressing gestational weight gain within antenatal practice is required, including asking about diet and exercise, for all women identifying as Indigenous Australian.

Keywords: Gestational weight gain; pregnancy; body mass index; Aborigines, Australian

Introduction Health outcomes for Aboriginal and Torres Strait Islander Australians, (hereafter referred to as Indigenous), are poor in comparison to non-Indigenous Australians, particularly outcomes related to the development of chronic diseases (Commonwealth of Australia, 2017). Pregnancy is considered one of the earliest stages in which programming for chronic disease occurs (Barker, 1998), with the timing of physiological weight gain linked to stages in fetal

development and reliant on the metabolisms of both mother and fetus (I.O.M. N.R.C. Committee, 2009). Ranges for healthy gestational weight gain have been specified by the 2009 Institute of Medicine (IOM) Pregnancy Weight Guidelines, which recommends weight gain in relation to pre-pregnancy body mass index (BMI) (I.O.M. N.R.C. Committee, 2009). Factors affecting gestational weight gain (GWG) in Indigenous Australian women include the physical, community and societal environment, along with maternal factors such as medical history, epigenetics, dietary intake and energy expenditure due to physical activity (I.O.M. N.R.C. Committee, 2009). Social and cultural determinants have been shown to affect the way First Nations women view their pregnancy in Canada (Darroch and Giles, 2016a, 2016b) and there are likely similarities with Australian Indigenous women. Determinants can include values and traditions associated with their culture, beliefs surrounding the physiological inevitabilities of pregnancy related to their ethnicity, such as weight gain or diabetes, and the role of other women in their community (Darroch and Giles, 2016b). The physical environment in which the woman is living, which includes social spaces, safety concerns and accessibility to services and facilities, can affect the amount of physical activity undertaken during her pregnancy (Laraia et al., 2007; Thompson et al., 2017). The influence of family and friends on decisions that influence dietary patterns may be a determinant of GWG (Keely et al., 2017; Farbu et al., 2014). Appropriate GWG is reliant on maintaining a balance between alterations in metabolism, energy expenditure and energy intake over the course of gestation. Changes in energy expenditure are driven by changes in basal metabolic rate and physical activity level (Butte et al., 2004). Physical activity levels tends to decrease over pregnancy, particularly in the third trimester, whilst resting energy expenditure increases (Butte et al., 2004). The increase in resting energy expenditure is due to increases in metabolically active fat-free mass, although this can vary according to individual fat mass (Berggren et al., 2017). Energy intakes higher than energy expenditure result in excess fat mass accumulation, not fat-free mass, especially in overweight and obese women (Berggren et al., 2016; Butte et al., 2003). The impact of inadequate or excessive GWG has both short and long-term consequences for both the mother and infant (Siega-Riz et al., 2009; Xu et al., 2017; Tsai et al., 2015; Han et al., 2011; Goldstein et al., 2017; Mamun et al., 2010; Mamun et al., 2014). Inadequate GWG increases the risk for preterm birth, low birthweight (LBW) (<2500grams) and infants who are small-for-gestational age (SGA) (Siega-Riz et al., 2009; Xu et al., 2017; Tsai et al., 2015; Han et al., 2011). There is evidence to suggest that inadequate weight gain also results in epigenetic changes within the placenta, although confirmation is required that the same occurs in the fetus (Kawai et al., 2015). Excessive GWG has associations with a range of adverse conditions during pregnancy and delivery, such as gestational diabetes, gestational hypertension, infants born large-forgestational age or with macrosomia, and increases in caesarean deliveries (Siega-Riz et al., 2009; Goldstein et al., 2017). Beyond pregnancy, women with excessive GWG are more likely to be overweight or obese in the long term (Mamun et al., 2010; Fraser et al., 2011;

Abebe et al., 2015). GWG, rather than pre-pregnancy body mass index (BMI) has been shown to be a strong indicator of post-partum weight retention (Rong et al., 2015). Breast feeding rates are lower in women who are obese (Marchi et al., 2015) and likely to be of shorter duration (Turcksin et al., 2014), thus maintaining an appropriate weight gain in pregnancy is needed to facilitate breastfeeding for some women. In regard to the offspring, the first 1000 days has been shown to have a substantial impact on infant development, particularly weight status (Woo Baidal et al., 2016; Karachaliou et al., 2015; Mamun et al., 2014). Excessive GWG is reported to increase the risk of offspring obesity by 40% (Mamun et al., 2014), particularly if the weight gain is excessive in the first trimester (Karachaliou et al., 2015). Of equal concern is the potential association between pre-pregnancy maternal adiposity and impaired development of brain white matter in the offspring (Ou et al., 2015), and it is currently unclear whether this association also relates to excessive GWG. Overall, evidence from non-Indigenous women shows that appropriate GWG plays an important role in the long-term health of both women and their offspring. Previous research and programs surrounding the health of Indigenous Australian mothers and children have to date predominantly focused on factors that have an immediate health impact, such as reducing morbidity and mortality of the offspring, improving rates of LBW and increased antenatal care (Jongen et al., 2014). Ethnicity in combination with pre-pregnancy BMI may contribute to inadequate GWG. African American and Hispanic women in the United States with a normal BMI were at greater risk of inadequate GWG compared to Caucasian women (Headen et al., 2015). Currently, there is a need to characterize patterns of GWG for Indigenous women and identify whether inadequate or excessive weight gain is potentially affecting the health of the women and their children. Therefore, the primary aim of the current study was to examine rates of gestational weight gain in a cohort of Indigenous Australian women by prepregnancy BMI categories, relative to national GWG recommendations (I.O.M. N.R.C. Committee, 2009). The secondary aim was to determine whether inadequate or excessive GWG is related to pre-pregnancy BMI in Australian Indigenous women from the same cohort. Methods Participants Data is from the [removed for blind review] program, a prospective longitudinal study that follows Indigenous women, or women carrying an Indigenous child, from pregnancy up until the child is five years of age. The detailed study methodology has been published elsewhere [reference removed for blind review]. Briefly, women are recruited to the study by Indigenous research staff in early pregnancy at antenatal clinics and services in three research sites in [removed for blind review], Australia. These sites were originally selected to access women from regional [removed for blind review], rural [removed for blind review] and remote [removed for blind review] communities in [removed for blind review].

Recruitment began in 2010 and has continued in the rural and remote communities, with the regional site being discontinued due to significant recruitment challenges. Included participants are provided with written and verbal information about the study and must provide written informed consent prior to joining the cohort. Women are eligible to join the study at any stage of their pregnancy and may also re-enroll for subsequent pregnancies. [Ethics statement removed for blind review]. Measures Women were asked to self-report demographic details on their first visit. This included their age, smoking status, pre-pregnancy weight and brief medical history questions, such as whether they had a diagnosis of diabetes, hypertension or kidney disease. Additionally, women were asked their pregnancy and childbirth history, which included the number times they had given birth, number of times they had been pregnant and number of multiple births. Data collection was planned for each trimester; however, appointments did not always coincide with specific trimester dates. Ultrasound data was sought for up to three visits. Scans were performed using a Phillips Cx50 Portable Diagnostic Ultrasound with a 5Mhz convex transducer. Gestational age was derived from either the first or the second scan, and was also used to screen for multiple fetuses. Maternal height was collected on the first visit in accordance with ISAK protocols (Stewart et al., 2011). Anthropometric data and smoking status was collected on the first and any subsequent visits. Women were designated as smokers if they indicated smoking at any point in their pregnancy. Body composition data was collected via impedance analysis using InBody 720 TM (Biospace Co., Ltd., Seoul, South Korea) and included weight and percentage fat and fat free mass. Body mass index (BMI) was calculated using height from first visit, using the formula of weight (kilograms) / height (meters)2. Only women who enrolled in the study after March 2013 were included for analysis, as this is when pregnancy weights using this method were introduced. Where possible, medical data relating to the birth outcome was collected from hospital birth records. This included whether the mother had developed gestational diabetes, gestational hypertension, preeclampsia or eclampsia. Gestational weight gain status Trimesters are defined as trimester 1: 0-12 weeks, trimester 2: 13-28 weeks and trimester 3: 29th week to birth (Tsai et al., 2015). Women who were not able to provide a pre-pregnancy weight but had a weight recorded from the first trimester, were assigned a weight according to the formula: [first weight measure (kg) - (1.00kg /estimated gestational age in weeks)], based on a median weight gain of 1kg in the first trimester (I.O.M. N.R.C. Committee, 2009). Women were categorized according to their pre-pregnancy BMI as being underweight (BMI<18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0-29.9

kg/m2) and obese (BMI ≥30.0 kg/m2) (I.O.M. N.R.C. Committee, 2009). Obese women were further categorized as obese Class 1 (BMI 30.0-34.9 kg/m2), obese Class 2 (BMI 35.0-39.9 kg/m2) and obese Class 3 (BMI ≥40.0 kg/m2) (Australian Government Department of Health). Mean, upper and lower recommended weight gain values were calculated based on mean and range values presented by 2009 IOM guidelines for weight gain during pregnancy and assumed a 0.5 – 2.0 kg weight gain in the first trimester (I.O.M. N.R.C. Committee, 2009). Statistical analysis Data was presented as mean ± standard deviation (mean±sd) when normally distributed, or otherwise presented as median (interquartile range) (med (IQR)). Women were categorized as having inadequate, adequate or excessive GWG, based on the last weight recorded in the study during their pregnancy, which was calculated according to the ranges presented for their pre-pregnancy BMI. Data from observations and reference ranges were presented visually using two-way quadratic prediction (based on linear regression) and scatter plots, by BMI category and hypertensive or diabetic status. Women with an appropriate GWG relative to recommendations were designated by a single data point. Women outside of the recommended range were designated with a line showing the distance to the upper or lower recommended weight gain limit for their individual pre-pregnancy weight. Mixed model linear regression with clustering for individuals over time was used to determine if gestational weight gain was related to pre-pregnancy BMI status. The model was adjusted for weeks of gestation, smoking status during pregnancy (yes/no), parity (nulliparous/multiparous), maternal age and hypertension and diabetes status. Analyses were performed using Stata/IC 13.1 for Windows (StataCorp, Texas, USA). Findings 257 pregnancies from 225 women enrolled in the study after 1st March, 2013. Four pregnancies were excluded due to multiple fetuses. Of these, 110 pregnancies from 98 women had a pre-pregnancy weight, BMI or a weight recorded within the first trimester and a weight measure from any point in the pregnancy available that could be used to show weight gain trajectories. Approximately 78% of women identified as being Aboriginal and 22% identified as carrying an Indigenous child. Demographics for the included women can be seen in Table 1. Table 1: Demographics for the study population.

Age (years) Number of women included for >1 pregnancy Number of children * Primiparous

Mean (sd) 25.1±6.1

n (%) 110 (100%) 12 (n/a)

1.9±2.2 14 (12.7%)

Mean (sd) Multiparous (missing) Indigenous status Indigenous Carrying an Indigenous child Education level
n (%) 57 (51.8%) 39 (35.5%) 86 (78.2%) 24 (21.8%) 13 (11.8%) 25 (23.6%) 17 (15.5%) 13 (11.8%) 4 (3.6%) 4 (3.6%) 33 (30%)

48.3±4.3 57.5±6.6 72.3±7.3 98.8±16.5 86.0±8.1 96.4±9.5 117.9±13.0

6 (5.5%) 33 (30.0%) 23 (20.9%) 48 (43.6%) 18 (16.4%) 16 (14.6%) 14 (12.7%) 14 (12.7%) 3 (2.7%) 0 (0%) 11 (10.0%) 16 (14.5%) 1 (0.9%) 5 (4.5%) 10 (9.1%) 33 (30%) 3 (2.7%)

35 (31.8%) 16 (14.6%) 59 (53.6%)

Figure 1 (a-g) shows trajectories of gestational weight gain within each BMI category, based on quadratic predictions for the observations in each category, and compared to recommended trajectories according to the 2009 IOM guidelines (I.O.M. N.R.C. Committee, 2009). As a BMI group, the graphs show that those at most risk of excessive gestational

weight gain are those categorized as underweight, normal weight and overweight by their pre-pregnancy BMI. Overall, within obese BMI categories (all three Classes) were estimated to have a GWG close to the recommendations, although it must be noted that very few individual women gained adequate amounts of weight. Figure 1 (a-g): Weight gain during pregnancy according to pre-pregnancy BMI. Dots represent women who were at an appropriate weight gain according to their pre-pregnancy BM. Colours of dots indicate whether their pregnancy was considered normal or had a hypertensive or diabetic status. Lines attached to the dots show the distance (weight in kg) to the nearest upper or lower recommended limit of weight gain for the individual.

Table 2 summarizes the percentage of recommended weight gain within each BMI category according to I.O.M. N.R.C. Committee (2009) categories of inadequate, adequate and excessive weight gain. Consistent percentages of inadequate weight gain can be seen in all pre-pregnancy BMI categories, both across trimesters 2-3 and at the last weight measure taken, and range from approximately 95-98% of recommended GWG. Similarly, the percentage of women with excessive GWG is also consistent among BMI classes, ranging from approximately 103%-109%. Results for those with an underweight pre-pregnancy BMI must be interpreted with caution, due to the low numbers for in this category. Table 2: Percentage of recommended weight gain by BMI category and IOM categories of inadequate, adequate and excessive gestational weight gain. Pre-pregnancy weight and weight of participants during trimesters is also provided.

Percentage of recommended weight gain at time of measurement BMI GWG category Trimester categor (IOM, 2009) at 2 y last obs. Wks Wks 13- 2120 28

1 Inadequat (17% e )

Prepregnanc y weight

Trimester 3 Wks At Wks 29last 35+ 34 obs.

← Median % →

n (%)

-

97% 96%

-

Weight of participants

Trimester 2

Wks Wks 2935+ 34 ← Median kg → (IQR)

96%

Under3 49.0 weight Adequate (50% N/A N/A N/A N/A N/A (45.0-51.0) (n=6) ) Excessive

2 (33%

-

104 108 108 109 % % % %

Trimester 3

Wks Wks 13-20 21-28

-

-

-

47.7 49.9 (N/A) (N/A)

N/A

56.2 (N/A)

64.0 66.3 (61.0- (64.1-

66.0 (62.0 66.7) 78.5 (N/A

)

67.0) 68.5)

11 Inadequat (33% 96% 98% 92% 96% 97% e )

60.2 61.2 62.5 (54.6- (58.9- (62.561.6) 62.2) 65)

Healthy 6 59.4 58.0 58.5 55.0 weight Adequate (18% N/A N/A N/A N/A N/A (55.6(54.2-61.5) (N/A) (N/A) (n=32) ) 69.4) 16 103 105 107 106 106 Excessive (48% % % % % % )

66.7 69.5 73.9 (55.9- (66.8- (68.077.4) 81.5) 78.7)

3 Inadequat (13% 97% 95% 95% 97% 95% e )

70.7 70.7 77.7 (57.9- (65.2- (70.083.4) 80.6) 85.3)

3 OverAdequate (13% N/A N/A N/A N/A N/A 70.0 Weight ) (68.0-78.0) (n=23)

-

63.9 86.9 (N/A) (N/A)

17 103 106 109 106 106 Excessive (74% % % % % % )

74.9 80.9 82.8 (73.8- (78.4- (77.780.8) 87.6) 92.4)

20 Inadequat (42% 98% 95% 96% 97% 97% e )

93.8 96.3 85.8 (78.2(91.1- (78.6122.1 104.4) 103.2) )

Obese Adequate 4 N/A N/A N/A N/A N/A (8%) (n=48)

24 107 107 107 106 106 Excessive (50% % % % % % )

95.8 (86.5110.0)

99.8 88.5 90.0 (86.9- (85.2- (87.7112.7) 95.5) 97.1)

) 65.9 (62.8 72.4) 65.9 (59.7 73.5) 81.7 (76.3 90.6) 86.6 (N/A ) 89.7 (77.2 94.8) 90.2 (83.4 91.8) 104.5 (95.0 113.6 ) 95.0 (88.8 95.9)

114.4 109 108.2 104.2 (93.8 (101.2 (103.9 (93.2118.9 129.6 114.1) 118.5) ) )

NOTE: N/A used to show where data is either not applicable or not available. Data may be unavailable due to the number of observations from which the data is derived.

In the linear mixed model regression, no significant differences were found between any of the pre-pregnancy BMI categories compared to normal weight (coef. -1.40, p=0.47, coef. -0.07, p=0.97, coef. -1.14, p=0.631, coef.-2.90, p=0.18 and coef -4.51, p=0.07) for underweight, overweight, obese Class 1, obese Class 2 and obese Class 3 respectively. However, in the same model, week of gestation explained a significant amount of variation in GWG (coef. 0.11, 95%CI 0.03-0.20, p<0.01), as did being multiparous (coef. 4.5, 95%CI: 1.30-7.71, p<0.01), or hypertensive (coef. 4.79, 95%CI: 0.23-9.35, p=0.040). No significant relationship was found with smoking status (coef. 1.76, p=0.25), maternal age (coef. -0.05, p=0.65) or diabetes status (coef. 4.44, p=0.09). Discussion Adequate GWG occurred in a minority of participants (15%), with most women either not gaining enough weight during their pregnancy (32%) or gaining weight above the 2009 I.O.M. recommended ranges (54%). The highest proportion of women gaining insufficient weight were those classified with an obese pre-pregnancy BMI (42%), while a high proportion of women gaining excessive gestational weight were predominantly found in those in the overweight (74%), healthy (48%) and obese categories (50%). There was no relationship between pre-pregnancy BMI status and GWG. Women who were multiparous or hypertensive were more likely to have higher GWG. GWG from other non-Indigenous culturally diverse Australian studies shows that rates of adequate GWG ranged from 34-38%, with excessive GWG in 41% and inadequate in 20% of pregnancies (Hartley et al., 2016; Cheney et al., 2017). In comparison to other Indigenous populations, American Indian or Alaskan Native people have been reported to have rates of 21% inadequate, 29% adequate and 50% excessive GWG (Rockhill et al., 2015). Rates of adequate GWG of other minority groups within the United States are also higher than the rates reported in Australia, with adequacy reported as 25% for African American women and 28% for women identifying as Hispanic (Headen et al., 2015). The low rate of adequate GWG in this population compared to national and international rates indicates an area where disparities between Indigenous and non-Indigenous Australian women may be reduced. Excessive GWG was found in 50% of the women with a healthy pre-pregnancy BMI and 74% in those categorized as overweight, much higher than values presented in another Australian population (30% and 43%, respectively) who were primarily non-Indigenous (1.6% Indigenous) (Cheney et al., 2017). Conversely, rates of excessive GWG in women with obesity were similar to other Australian cohorts, with 50% reported in the current cohort, compared to 46% reported by Cheney et al (2017). Findings suggesting that parity contributed to GWG is consistent with other Australian data. Rates of adequate GWG in primiparous women were 46% compared to 32% in multiparous women (Hartley et al., 2016). Hartley et al. (2016) also found higher rates of inadequate and excessive GWG with higher parity status. Inadequate GWG was reported for 18% of primiparous women and 22% of multiparous women, with excessive GWG reported in 36% of primiparous and 46% of multiparous women (Hartley et al., 2016). National data reports

that the average number of babies born to Indigenous women in 2015 was 2.3 (Australian Bureau of Statistics, 2015), with 1.9±2.2 in the current population sample. One of the most likely outcomes for the mothers with excessive GWG is higher post-partum weight retention (Martin et al., 2014; Abebe et al., 2015; Fraser et al., 2011). In Australia, perinatal care can be supported by primary health care providers, including general practitioners, midwives and child health nurses (Miller et al., 2014). However, it has been identified that a number of barriers inhibit the systematic provision of advice in regards to GWG, which includes difficulty in raising the sensitive subject of overweight and obesity, insufficient consultation times or low demand from the women themselves (Miller et al., 2014). Additionally, healthcare professionals might not prioritize diet and GWG (Waller et al., 2016). Diet and weight gain was reported to be less frequently asked about in a large tertiary Australian hospital in comparison to blood pressure and smoking status with 99% asked about blood pressure, 97% about smoking status, 65% women asked about diet and 56% asked about weight gain (Jongen et al., 2014). Whilst Indigenous women may not attend antenatal classes as frequently compared to nonAboriginal women for a variety of reasons, approximately 70% of women attend at least one antenatal visit (Murphy and Best, 2012). However, it is unclear whether advice regarding GWG is systematically offered, given the importance of other maternal and child outcomes for Indigenous Australians that must be addressed in care (Jongen et al., 2014). A number of factors are likely to influence why this group of women did not meet adequate weight gain targets for their pregnancies. Diet may potentially change with the knowledge of being pregnant (Hillier and Olander, 2017), and the type of dietary changes may depend on income as a contributing factor (Cheney et al., 2017). However, the changes in this cohort are unknown to date. National data in 2015 indicated that two thirds (68%) of the Indigenous Australian population had a weekly income of less than $600 per week (Australian Institute of Health and Welfare, 2015). Additionally, dietary intakes of Indigenous Australians, particularly in relation to fruit and vegetables, are likely to be inadequate compared to recommendations for good health (Australian Institute of Health and Welfare, 2015). Paul et al. (2013) reported changes in diet during pregnancy being related to income in the United States. High-income women focused on modifying their nutrient intakes, and avoiding foods potentially harboring listeria, such as soft cheeses and processed meats and known to increase risk to the fetus (Paul et al., 2013). In contrast, low income women prioritized abstaining from alcohol and initiating or increasing intakes of fruits and vegetables (Paul et al., 2013). A number of challenges are associated with counselling for gestational weight gain, particularly for those who may already be overweight or obese (Dodd and Briley, 2017; Hill et al., 2017). Weight gain due to pregnancy may not be viewed as a concern, rather considered as a normal consequence of having children (Hill et al., 2017; Dodd and Briley, 2017) or as a time to relax weight gain restraints or eating habits (Hill et al., 2017). The current study raises the question as to the type of advice that should to be offered concerning adequate GWG, as well as the type and intensity of services required and whether

this would be acceptable to Indigenous women. A meta-analysis of interventions for managing GWG through diet and physical activity showed that focusing on these factors is effective, but variable in results and active ingredients are difficult to identify (Gardner et al., 2011). It was suggested that health behaviors cluster, and yet the evidence is unclear as to whether it is more effective to focus on a single behavior change, or target multiple health changes at once (Gardner et al., 2011). Pregnancy is a time of many changes and the potential exists that targeting multiple changes during this time for this cohort of women may lead to confusion, set unrealistic goals and disengage them from the process (Gardner et al., 2011). One of the inherent limitations measuring GWG is that women self-report their weight prior to pregnancy. It has been estimated that women under-report their weight by approximately 0.7-1.4kg (Pursey et al., 2014). Whilst approximately 90% of pregnant women have been shown to be correctly categorized using self-report data (Masiero et al., 2014), the actual number of women incorrectly categorized here is unclear. Additionally, whilst the study endeavors to obtain measures from women in each trimester, this is not always possible. Therefore, weight data available at each trimester period may come from a low number of women at each time point. Additionally, insufficient data was available to report on whether rates of excessive GWG occurred during trimester one and continued for trimesters two and three (Cheney et al., 2017), which may impact on obesity in the offspring (Gaillard et al., 2015; Karachaliou et al., 2015). It is also difficult to quantify the impact of hyperemesis gravidarum on GWG (I.O.M. N.R.C. Committee, 2009). Conclusion The current study highlights the need to focus on optimizing GWG for Indigenous Australian women as few gained weight consistent with recommendations based on pre-pregnancy BMI category. Further research is required to investigate the types of interventions that are culturally acceptable to achieve optimal GWG in Indigenous women.

Acknowledgements The authors would like to acknowledge the guidance, support and commitment from members of the [removed for blind review] Aboriginal Steering committee. 1. Ethical Approval Ethics approval for this project was provided by the Hunter New England (HNE) Local Health District Human Research Ethics Committee (HREC) (reference number: 08/05/21/4.01), the NSW HREC (reference number: HREC/08/HNE/129, and the Aboriginal Health and Medical Research Council (reference number: 654/08). 2. Funding sources The National Health and Medical Research Council (Australia) have provided the primary funding for this work (Grant numbers: 569239, APP1004181, APP1063123). Other funding for the Gomeroi gaaynggal research project includes funding from Kidney Health Australia

and the Hunter Medical Research Institute. No funding has been provided for publishing in open access journals. K.G.P. is funded by an Australian Research Council Future Fellowship (FT150100179). C.E.C. is supported by a National Health and Medical Research Council of Australia Senior Research Fellowship and a Gladys M Brawn Senior Fellowship from the University of Newcastle. 3. Clinical trial registry N/A

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40

50

Weight (kg) 60 70

80

Underweight

0

10

20 Weeks of gestation

30

40

40

Weight (kg) 80 60

100

Normal weight

0

10

20 Weeks of gestation

30

40

30

40

30

40

30

40

60

Weight (kg) 80 90 70

100

Overweight

0

10

20 Weeks of gestation

60

80

Weight (kg) 100 120

140

Obese class 1

0

10

20 Weeks of gestation

80

90

Weight (kg) 100 110 120

130

Obese class 2

0

10

20 Weeks of gestation

100

Weight (kg) 140 120

160

Obese class 3

0

10

20 Weeks of gestation

30

40

30

40

60

80

Weight (kg) 100 120 140

160

All obese categories

0

10

20 Weeks of gestation

Key Average participant weight gain Normal pregnancy Diabetes disorder

Recommended weight gain Hypertensive disorder