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The relationship between pregnancy intention and change in perinatal cigarette smoking: An analysis of PRAMS data
Journal of Substance Abuse Treatment 46 (2014) 189–193
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Journal of Substance Abuse Treatment
The relationship between pregnancy intention and change in perinatal cigarette smoking: An analysis of PRAMS data Margaret S. Chisolm, M.D. a,⁎, Diana Cheng, M.D. b, Mishka Terplan, M.D., M.P.H. c a b c
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA Office of Surveillance and Quality Initiatives, Maternal and Child Health Bureau, Maryland Department of Health and Mental Hygiene, Baltimore, MD, USA Departments of Obstetrics, Gynecology, and Reproductive Sciences, and Epidemiology, University of Maryland School of Medicine, Baltimore, MD, USA
a r t i c l e
i n f o
Article history: Received 17 December 2012 Received in revised form 10 June 2013 Accepted 21 July 2013 Keywords: Smoking Pregnancy Family planning Epidemiology
a b s t r a c t This study examined the relationship between pregnancy intention and change in perinatal cigarette smoking from a large national sample of women in the United States, the 2004–2008 Pregnancy Risk Assessment Monitoring System (PRAMS). The study sample consisted of 49,510 female smokers. Smoking rates and quantities were captured prior to pregnancy, the last 3 months of pregnancy, and postpartum. Changes in smoking were compared between pregnancies classified as intended, mistimed, and unwanted. Regardless of pregnancy intention status, most behavior change happened before the final 3 months of pregnancy. Overall, most women were able to quit or reduce smoking. However women with unwanted pregnancies had 0.86 times the adjusted odds of quitting/reducing cigarette smoking compared to women with intended or mistimed pregnancies (95% CI: 0.78, 0.95). Findings suggest early smoking cessation interventions lead to greater change in smoking, regardless of pregnancy intention, although change is more difficult for women with unwanted pregnancies. © 2013 Elsevier Inc. All rights reserved.
1. Introduction In the United States (U.S.), approximately 22% of reproductive age women smoke cigarettes (Centers for Disease Control and Prevention (CDC), 2008). Cigarette smoking during pregnancy is the largest modifiable risk factor for pregnancy-related morbidity and mortality (Benowitz & Dempsey, 2004). It is known to increase risk of impaired fetal growth, pre-term birth, and low birth weight, in addition to other adverse pregnancy and neonatal outcomes (Bada et al., 2005; Conter, Cortinovis, Rogari, & Riva, 1995; Knopik et al., 2005; Salihu et al., 2008; Stroud et al., 2009; Thiriez et al., 2009). Although the harmful consequences of cigarette smoking while pregnant are well known, smoking during pregnancy remains a serious public health problem. About 12.8% of women continue to smoke cigarettes during pregnancy (Tong et al., 2009), a percentage which varies greatly by region (e.g., 5.2% in New York City, 35.7% in West Virginia) (Tong et al., 2009). Such estimates of the prevalence of cigarette smoking in pregnancy are based on self-report and most likely represent an under-estimation of true prevalence (Burstyn et al., 2009). Although not all women achieve success at quitting, 8.5%–39.1% pregnant women have reportedly been able to reduce the number of cigarettes smoked (Adams et al., 1992; Massey et al., 2011; Windsor, Woodby, Miller, & Hardin, 2011), and reduction in cotinine levels (a biochemical measure of
⁎ Corresponding author. Tel.: +1 410 550 9744; fax: +1 410 550 2552. E-mail address: [email protected] (M.S. Chisolm). 0740-5472/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jsat.2013.07.010
smoke exposure) has been associated with improved pregnancy outcomes (Oncken et al., 2008). Many factors are known to affect likelihood of success in smoking cessation, including low socioeconomic status, lack of social support, exposure to stress, depressed mood, and/or low motivation (Echer & Barreto, 2008; Hiscock, Bauld, Amos, Fidler, & Munafo, 2012; Murray, Johnston, Dolce, Lee, & O'Hara, 1995; Stewart et al., 2011). Some of the factors related to low socioeconomic status, such as non-white race, less educational attainment, younger age, unmarried, Medicaid insurance, and lower income, are also related to pregnancy intention status (Afable-Munsuz & Braveman, 2008; Cheng, Schwarz, Douglas, & Horon, 2009; Mohllajee, Curtis, Morrow, & Marchbanks, 2007) and, independent of intention status, to adverse pregnancy outcomes (Luo, Wilkins, Kramer, & Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System, 2004; O'Campo, Xue, Wang, & Caughy, 1997). Of note, unintended pregnancy status may be a stressor unto itself, which may further contribute to adverse outcomes (Maxson & Miranda, 2002). Compared to women who intend to be pregnant, women with unintended pregnancies may be less able to modify harmful health behaviors, such as cigarette smoking, prior to conception (Altfeld, Handler, Burton, & Berman, 1997; Chuang et al., 2010; Dott, Rasmussen, Hogue, Reefhuis, & National Birth Defects Prevention Study, 2010). Once aware of being pregnant, women with unintended pregnancies are less able to reduce smoking compared to women with intended pregnancies (Cheng et al., 2009; Kost, Landry, & Darroch, 1998; Orr, James, & Reiter, 2008). Because half of all pregnancies in the
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U.S. are unintended (Finer & Zolna, 2011), the personal and public health impact of both unintended pregnancies and perinatal cigarette smoking on adverse maternal and neonatal outcomes is huge (Orr et al., 2008). Prior research has demonstrated that female smokers who are trying to get pregnant are more likely to quit than if not attempting pregnancy (Chuang, Hillemeier, Dyer, & Weisman, 2011). However, no large-scale study of nationally representative samples has yet examined the relationship between pregnancy intention and cigarette smoking throughout the perinatal period: from prior to pregnancy through postpartum. The current study analyzed data from the Pregnancy Risk Assessment Monitoring System (PRAMS). PRAMS is a national surveillance system designed to monitor self-reported behaviors, health care use, and morbidities of women before, during, and after pregnancy. The availability of data that permit comparisons of behaviors from pre-pregnancy, during pregnancy, and postpartum represents an opportunity to investigate the relationship between pregnancy intention and cigarette smoking behavior change. The study hypothesized that cigarette-smoking women with intended/mistimed pregnancies will report greater reduction in cigarette smoking during pregnancy compared to women with unwanted pregnancies. 2. Materials and methods 2.1. Study design The 2004–2008 PRAMS collected data from a nationally representative sample of postpartum women, with nearly all geographic regions of the country assessed (33 states and New York City). PRAMS is an ongoing state- and population-based surveillance project of the Centers for Disease Control and Prevention and state health departments designed to monitor selected maternal behaviors and experiences that occur before, during, and shortly after pregnancy among women who deliver live-born infants in the U.S. Each state uses a monthly stratified sample system to survey 100–300 new mothers two to 9 months after delivery. Women who do not respond to two or three mailings are contacted by telephone to complete the survey. Survey data are linked to selected birth certificate data and weighted for sample design, non-response, and non-coverage. The weighted data represent all women delivering live infants in the respective state in the given year. Details about the PRAMS design and methods are available elsewhere (Shulman, Gilbert, Msphbrenda, & Lansky, 2006). The PRAMS project has been approved by the CDC institutional review board. The University of Maryland, the Maryland Department of Health and Mental Hygiene, and the Johns Hopkins University Institutional Review Boards exempted the current study from IRB approval.
be pregnant then or at any time in the future" were classified as unwanted. For the binary analysis intended and mistimed pregnancies were grouped together and contrasted with unwanted pregnancies. These variable definitions correspond to those in the existing literature and the decision to dichotomize the variables was made in order to better isolate the different life-choice considerations captured in pregnancy intention measurements (Luker, 1999; Santelli et al., 2003; Shah et al., 2011). Cigarette smoking behavior was assessed by several questions. Respondents were asked to endorse a category reflecting the average number of cigarettes (CPD) smoked daily in the 3 months prior to pregnancy, the last 3 months of pregnancy, and postpartum. Variables were constructed to reflect smoking behavior change at each of these time points. Smoking change in pregnancy was assessed by comparing the reported CPD category in the three months prior to pregnancy to the CPD category in the last 3 months of pregnancy. Smoking change postpartum was assessed by comparing the reported CPD category in the last 3 months of pregnancy to that reported postpartum. Overall smoking behavior change was assessed by comparing the reported CPD category 3 months prior to pregnancy to postpartum. (Thus, overall smoking change includes women who quit and stayed quit, as well as women who quit and relapsed.) For each of the time points the following variables were defined: individuals who reported no cigarettes were designated as quit; those that reported a change to a category of CPD that reflected reduced smoking were designated as reduced; and those who reported no change in category or a change to a category of CPD that reflected increased smoking were designated as same/more. For the logistic regression analyses, the categories quit and reduced were grouped together and contrasted with same/more. 2.3. Data analysis Population adjusted proportions with 95% confidence intervals (CI) were computed using the population weight assigned to each observation in the PRAMS data set. Bivariate analysis was performed comparing pregnancies that were classified as intended/mistimed versus unwanted using the chi-square statistic for select demographic factors. Stratum-specific odds ratios were examined for homogeneity using the Breslow-Day test with a p value of less than 0.05 considered as evidence of effect modification. Next, crude odds ratios were computed via logistic regression to determine the odds of smoking behavior change by pregnancy intention. Backwards logistic regression was then manually performed adjusting for important potential confounders, using change-inestimate criteria of 10%. 3. Results
2.2. Measures 3.1. Demographic characteristics Sample inclusion criterion was limited to those respondents who reported any cigarette consumption in the 3 months prior to pregnancy, after responding in the affirmative to the screening question, “Have you smoked at least 100 cigarettes in the past 2 years?” Demographic and background characteristics collected in PRAMS included variables generated from birth certificates (e.g., pre-term or term delivery status, age, education, race/ethnicity, parity, marital status) and from questionnaire (e.g., income, health insurance, prenatal care health behaviors, and birth outcomes). Pregnancy intention was assessed by response to the following PRAMS survey question: "Thinking back to just before you got pregnant with your new baby, how did you feel about getting pregnant?" [emphasis in original]. Those who responded "I wanted to be pregnant then" or "I wanted to be pregnant sooner" were classified as intended pregnancies. Those who responded "I wanted to be pregnant later" were classified as mistimed. Those who responded "I didn't want to
The final sample consisted of 49,510 women who had a recent live birth and self-reported any cigarette smoking in the 3 months prior to pregnancy. The sample represented a population that was approximately 76% White, 12% Black, 7% Hispanic, and 5% other racial groups. Approximately 13% of the sample was less than 20 years of age, 35% ages 20–24, 29% ages 25–29, and 23% age 30 or older. Approximately 75% had at least 12 years of education and 57% were unmarried. Table 1 summarizes these demographic and other background characteristics from the weighted estimates of the sample. 3.2. Smoking behavior change by pregnancy intention Table 2 presents estimates of cigarette smoking behavior change measured at different pregnancy time points (as defined in section 2.2) and stratified by pregnancy intention (intended, mistimed,
M.S. Chisolm et al. / Journal of Substance Abuse Treatment 46 (2014) 189–193 Table 1 Demographic and background characteristics of sample. Demographic or background characteristic
% (95% CI)
Race/Hispanic origin White, non-Hispanic Black, non-Hispanic Hispanic Other, non-Hispanic Age (years) Less than 20 20–24 25–29 30 or older Education (ages 20+) Less than 12 years 12 years or higher Marital status Unmarried Married Income year prior to delivery Less than $10,000 $10,000–14,999 $15,000–24,999 $25,000–50,000 Greater than $50,000 Insurance prior to pregnancy Yes No Medicaid enrollment Yes No Timing of prenatal care (PNC) First trimester Second or third trimester Never initiated Smoking discussed in PNC Yes No Pre-term delivery Less than 37 weeks Less than 34 weeks Breastfed Ever Never
76.4 (75.8, 77.0) 11.9 (11.4, 12.4) 6.5 (6.1, 6.9) 5.3 (5.0, 5.6) 12.9 35.1 28.9 23.1
(12.4, (34.3, (28.2, (22.5,
13.5) 35.8) 29.6) 23.8)
24.2 (23.6, 24.9) 75.8 (75.1, 76.5) 57.1 (56.4, 57.9) 42.9 (42.1, 43.6) 29.5 13.2 17.2 20.7 19.5
(28.7, (12.6, (16.6, (20.1, (18.9,
30.2) 13.7) 17.8) 21.4) 20.2)
45.6 (44.9, 46.4) 54.4 (53.6, 55.1) 61.4 (60.6, 62.1) 38.6 (37.9, 39.4) 76.5 (75.8, 77.1) 22.5 (21.8, 23.1) 1.1 (0.9, 1.3) 85.4 (34.9, 86.0) 14.6 (14.1, 15.2) 10.2 (9.8, 10.6) 2.7 (2.6, 2.9) 63.4 (62.6, 64.2) 36.6 (35.8, 37.4)
and unwanted). The bulk of smoking behavior change occurred during pregnancy (from 3 months prior to pregnancy to last 3 months of pregnancy) and this change was greatest among women with either intended or mistimed pregnancies. Only 18% of women with intended pregnancies and 17% of those with mistimed pregnancies continued to smoke at the same level or greater compared to 28% of women with unwanted pregnancies (p b 0.001). However, these behavioral changes were not observed between the last 3 months of pregnancy to the postpartum period (p = 0.524). When compar-
Table 2 Cigarette smoking behavior change by pregnancy intention status. Cigarette smoking behavior change During pregnancy Quit Reduced Same/More Postpartum Quit Reduced Same/More Overall Quit Reduced Same/More
Intended (%)
Mistimed (%)
Unwanted (%)
p value
49.4 32.6 18.0
44.7 38.0 17.3
33.9 38.2 28.0
b0.001
5.1 5.3 89.7
4.5 5.4 90.1
4.6 6.2 89.2
0.524
28.8 23.8 47.4
22.1 27.1 50.8
17.3 23.7 59.0
b0.001
191
ing smoking behavior across the entire course of pregnancy (from 3 months prior to pregnancy to postpartum), 10% fewer women with intended or mistimed pregnancies smoked at the same level as they did prior to pregnancy compared to women with unwanted pregnancies (47.4 or 50.8 vs. 59.0%) (p b 0.001). Of note, the “reduced” change status demonstrated the least change across pregnancy time points and by pregnancy intention groups compared with either “quit” or “same/more.” Table 3 presents the crude and adjusted odds ratios of smoking behavior change by pregnancy intention status. For the purpose of this analysis, overall smoking change was used (i.e., smoking change from 3 months prior to pregnancy to postpartum). Women with unwanted pregnancies had 0.67 times the odds of quitting or reducing smoking compared to women with intended/mistimed pregnancies (95% CI: 0.61, 0.73). After adjusting for confounders, the odds shifted towards the null value but remained significant (0.86 [95%CI: 0.78, 0.95]). Controlling for other factors in the model, women with at least a high school education had a greater likelihood of quitting or reducing compared to women with less education. In contrast, women with Medicaid, as well as those with a prior birth, had a lower likelihood of quitting or reducing. Compared with White Non-Hispanic women, Black Non-Hispanic women had a lower likelihood of quitting or reducing smoking whereas other racial/ethnic groups had a higher likelihood.
4. Discussion 4.1. Conclusions To the authors’ knowledge, this is the first study to look at how pregnancy intention modifies change in cigarette smoking behavior throughout the perinatal time period. Using a nationally representative sample revealed that women with unwanted pregnancies were less likely to quit or reduce cigarette smoking compared with women with intended or mistimed pregnancies. Additionally we found that among women who reported smoking in the 3 months prior to pregnancy, the bulk of behavior change happened relatively early in pregnancy, before the final 3 months. Our findings are consistent with those of previous studies showing that women with intended pregnancies are more likely to engage in health-promoting behaviors, such as adherence to prenatal care
Table 3 Weighted estimates of odds ratios for cigarette smoking behavior change by pregnancy intention status (unwanted vs. intended/mistimed pregnancies). OR (95% CI) Crude odds ratio Unwanted pregnancy Adjusted odds ratio Unwanted pregnancy Parous - prior birth Medicaid High school education Race Black/NHa compared with White/NH Hispanic compared with White/NH Other/NH compared with White/NH Income Less than $10,000/year compared with more than $50,000/year $10–14,000/year compared with more than $50,000/year $15–24,000/year compared with more than $50,000/year $25–50,000/year compared with more than $50,000/year Age Less than 20 years compared with 30 years or older 20–24 compared with 30 years or older 25–29 compared with 30 years or older a
NH = Non-Hispanic.
0.67 (0.61, 0.73) 0.86 0.48 0.89 1.38
(0.78, (0.44, (0.81, (1.26,
0.95) 0.54) 0.97) 1.51)
0.76 (0.68, 0.85) 1.49 (1.29, 1.73) 1.20 (1.04, 1.38) 0.73 0.73 0.75 0.81
(0.64, (0.63, (0.66, (0.72,
0.84) 0.84) 0.86) 0.91)
0.68 (0.59, 0.78) 0.81 (0.74, 0.90) 1.05 (0.96, 1.15)
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appointments, good nutrition, and smoking cessation, compared to women with unwanted pregnancies (Altfeld et al., 1997; Cheng et al., 2009; Chuang et al., 2010; Dott et al., 2010; Kost et al., 1998; Orr et al., 2008). However these findings add to current knowledge by documenting minimal variability between the pregnancy intention categories of intended and mistimed. For example, overall rates of quitting or cutting back were not significantly different during pregnancy and postpartum between women with intended versus mistimed pregnancies but were different when compared with unwanted pregnancies. In other words, a pregnancy classified as unwanted has a stronger negative impact on changing unhealthy smoking behavior than intended or mistimed pregnancies. The results indicate that approximately 5–6% of women reported quitting or reducing cigarette smoking during the postpartum period, regardless of pregnancy intention status. The postpartum period is not typically associated with smoking reduction/cessation and, in fact, is associated with a high prevalence of smoking relapse (Ebrahim & Gfroerer, 2003). However, for some women, the postpartum appears to be a time of healthy change and so offer another window of opportunity in which providers can encourage women, with intended, mistimed, and unwanted pregnancies, to quit or reduce smoking. 4.2. Strengths and limitations This study has several important strengths, including in-depth analyses of pregnancy intention and perinatal cigarette smoking behavior change data collected from a large nationally representative sample. Furthermore, the study examined three categories of pregnancy intention (intended, mistimed, and unwanted) and assessed specific types of cigarette smoking behavior change (quit smoking, reduced smoking, and smoking more or no change) at three perinatal time intervals (during pregnancy, postpartum, and overall). Despite these strengths, there are several limitations to be considered when evaluating the study findings. First, pregnancy intention status and CPD are both based on self report, which for cigarette smoking most likely represents an under-estimation of the true prevalence of perinatal cigarette smoking behavior (Burstyn et al., 2009). Second, the questionnaire is retrospectively completed by postpartum women recalling behaviors, health care use, and morbidities that occurred before, during, and after pregnancy, thus increasing the likelihood of recall bias and other inaccuracies. Third, the phase 5 PRAMS questionnaire does not specifically ask women when they became aware of being pregnant, leaving the definition of pre-pregnancy open to interpretation, which may result in over-reporting of smoking cessation and reduction during the first 3 months of pregnancy. For that reason, future phases of PRAMS will include a question about timing of pregnancy awareness. Fourth, PRAMS data are collected only from women who deliver live births, thus the data are not generalizable to women who have still births or miscarriages, which may result in under-sampling of adverse pregnancy outcomes, particularly stillbirth, which is associated with perinatal cigarette smoking. Finally, the overall smoking behavior change measure included women who quit and stayed quit, as well as those who quit and relapsed, and these two behaviors may be operating differently by pregnancy intention status. In conclusion, this is the first study to provide estimates of cigarette smoking behavior change among U.S. women across three categories of pregnancy intention and three perinatal time intervals. Perinatal cigarette smoking and unwanted pregnancies are both highly prevalent public health problems in the U.S. Half of pregnancies in the US are unplanned and only half of all women who smoke cigarettes are able to quit during pregnancy. Viewing cigarette smoking and pregnancy intention through a health behavior lens may help treatment providers discover clues to solving both of these highly prevalent and problematic behaviors. In the meantime,
smoking cessation interventions timed to pre- and early pregnancy care appear more likely to lead to reduction or cessation in cigarette smoking, regardless of pregnancy intention, although change may be more difficult among women with unwanted pregnancies.
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Contents lists available at ScienceDirect
Journal of Substance Abuse Treatment
The relationship between pregnancy intention and change in perinatal cigarette smoking: An analysis of PRAMS data Margaret S. Chisolm, M.D. a,⁎, Diana Cheng, M.D. b, Mishka Terplan, M.D., M.P.H. c a b c
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA Office of Surveillance and Quality Initiatives, Maternal and Child Health Bureau, Maryland Department of Health and Mental Hygiene, Baltimore, MD, USA Departments of Obstetrics, Gynecology, and Reproductive Sciences, and Epidemiology, University of Maryland School of Medicine, Baltimore, MD, USA
a r t i c l e
i n f o
Article history: Received 17 December 2012 Received in revised form 10 June 2013 Accepted 21 July 2013 Keywords: Smoking Pregnancy Family planning Epidemiology
a b s t r a c t This study examined the relationship between pregnancy intention and change in perinatal cigarette smoking from a large national sample of women in the United States, the 2004–2008 Pregnancy Risk Assessment Monitoring System (PRAMS). The study sample consisted of 49,510 female smokers. Smoking rates and quantities were captured prior to pregnancy, the last 3 months of pregnancy, and postpartum. Changes in smoking were compared between pregnancies classified as intended, mistimed, and unwanted. Regardless of pregnancy intention status, most behavior change happened before the final 3 months of pregnancy. Overall, most women were able to quit or reduce smoking. However women with unwanted pregnancies had 0.86 times the adjusted odds of quitting/reducing cigarette smoking compared to women with intended or mistimed pregnancies (95% CI: 0.78, 0.95). Findings suggest early smoking cessation interventions lead to greater change in smoking, regardless of pregnancy intention, although change is more difficult for women with unwanted pregnancies. © 2013 Elsevier Inc. All rights reserved.
1. Introduction In the United States (U.S.), approximately 22% of reproductive age women smoke cigarettes (Centers for Disease Control and Prevention (CDC), 2008). Cigarette smoking during pregnancy is the largest modifiable risk factor for pregnancy-related morbidity and mortality (Benowitz & Dempsey, 2004). It is known to increase risk of impaired fetal growth, pre-term birth, and low birth weight, in addition to other adverse pregnancy and neonatal outcomes (Bada et al., 2005; Conter, Cortinovis, Rogari, & Riva, 1995; Knopik et al., 2005; Salihu et al., 2008; Stroud et al., 2009; Thiriez et al., 2009). Although the harmful consequences of cigarette smoking while pregnant are well known, smoking during pregnancy remains a serious public health problem. About 12.8% of women continue to smoke cigarettes during pregnancy (Tong et al., 2009), a percentage which varies greatly by region (e.g., 5.2% in New York City, 35.7% in West Virginia) (Tong et al., 2009). Such estimates of the prevalence of cigarette smoking in pregnancy are based on self-report and most likely represent an under-estimation of true prevalence (Burstyn et al., 2009). Although not all women achieve success at quitting, 8.5%–39.1% pregnant women have reportedly been able to reduce the number of cigarettes smoked (Adams et al., 1992; Massey et al., 2011; Windsor, Woodby, Miller, & Hardin, 2011), and reduction in cotinine levels (a biochemical measure of
⁎ Corresponding author. Tel.: +1 410 550 9744; fax: +1 410 550 2552. E-mail address: [email protected] (M.S. Chisolm). 0740-5472/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jsat.2013.07.010
smoke exposure) has been associated with improved pregnancy outcomes (Oncken et al., 2008). Many factors are known to affect likelihood of success in smoking cessation, including low socioeconomic status, lack of social support, exposure to stress, depressed mood, and/or low motivation (Echer & Barreto, 2008; Hiscock, Bauld, Amos, Fidler, & Munafo, 2012; Murray, Johnston, Dolce, Lee, & O'Hara, 1995; Stewart et al., 2011). Some of the factors related to low socioeconomic status, such as non-white race, less educational attainment, younger age, unmarried, Medicaid insurance, and lower income, are also related to pregnancy intention status (Afable-Munsuz & Braveman, 2008; Cheng, Schwarz, Douglas, & Horon, 2009; Mohllajee, Curtis, Morrow, & Marchbanks, 2007) and, independent of intention status, to adverse pregnancy outcomes (Luo, Wilkins, Kramer, & Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System, 2004; O'Campo, Xue, Wang, & Caughy, 1997). Of note, unintended pregnancy status may be a stressor unto itself, which may further contribute to adverse outcomes (Maxson & Miranda, 2002). Compared to women who intend to be pregnant, women with unintended pregnancies may be less able to modify harmful health behaviors, such as cigarette smoking, prior to conception (Altfeld, Handler, Burton, & Berman, 1997; Chuang et al., 2010; Dott, Rasmussen, Hogue, Reefhuis, & National Birth Defects Prevention Study, 2010). Once aware of being pregnant, women with unintended pregnancies are less able to reduce smoking compared to women with intended pregnancies (Cheng et al., 2009; Kost, Landry, & Darroch, 1998; Orr, James, & Reiter, 2008). Because half of all pregnancies in the
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U.S. are unintended (Finer & Zolna, 2011), the personal and public health impact of both unintended pregnancies and perinatal cigarette smoking on adverse maternal and neonatal outcomes is huge (Orr et al., 2008). Prior research has demonstrated that female smokers who are trying to get pregnant are more likely to quit than if not attempting pregnancy (Chuang, Hillemeier, Dyer, & Weisman, 2011). However, no large-scale study of nationally representative samples has yet examined the relationship between pregnancy intention and cigarette smoking throughout the perinatal period: from prior to pregnancy through postpartum. The current study analyzed data from the Pregnancy Risk Assessment Monitoring System (PRAMS). PRAMS is a national surveillance system designed to monitor self-reported behaviors, health care use, and morbidities of women before, during, and after pregnancy. The availability of data that permit comparisons of behaviors from pre-pregnancy, during pregnancy, and postpartum represents an opportunity to investigate the relationship between pregnancy intention and cigarette smoking behavior change. The study hypothesized that cigarette-smoking women with intended/mistimed pregnancies will report greater reduction in cigarette smoking during pregnancy compared to women with unwanted pregnancies. 2. Materials and methods 2.1. Study design The 2004–2008 PRAMS collected data from a nationally representative sample of postpartum women, with nearly all geographic regions of the country assessed (33 states and New York City). PRAMS is an ongoing state- and population-based surveillance project of the Centers for Disease Control and Prevention and state health departments designed to monitor selected maternal behaviors and experiences that occur before, during, and shortly after pregnancy among women who deliver live-born infants in the U.S. Each state uses a monthly stratified sample system to survey 100–300 new mothers two to 9 months after delivery. Women who do not respond to two or three mailings are contacted by telephone to complete the survey. Survey data are linked to selected birth certificate data and weighted for sample design, non-response, and non-coverage. The weighted data represent all women delivering live infants in the respective state in the given year. Details about the PRAMS design and methods are available elsewhere (Shulman, Gilbert, Msphbrenda, & Lansky, 2006). The PRAMS project has been approved by the CDC institutional review board. The University of Maryland, the Maryland Department of Health and Mental Hygiene, and the Johns Hopkins University Institutional Review Boards exempted the current study from IRB approval.
be pregnant then or at any time in the future" were classified as unwanted. For the binary analysis intended and mistimed pregnancies were grouped together and contrasted with unwanted pregnancies. These variable definitions correspond to those in the existing literature and the decision to dichotomize the variables was made in order to better isolate the different life-choice considerations captured in pregnancy intention measurements (Luker, 1999; Santelli et al., 2003; Shah et al., 2011). Cigarette smoking behavior was assessed by several questions. Respondents were asked to endorse a category reflecting the average number of cigarettes (CPD) smoked daily in the 3 months prior to pregnancy, the last 3 months of pregnancy, and postpartum. Variables were constructed to reflect smoking behavior change at each of these time points. Smoking change in pregnancy was assessed by comparing the reported CPD category in the three months prior to pregnancy to the CPD category in the last 3 months of pregnancy. Smoking change postpartum was assessed by comparing the reported CPD category in the last 3 months of pregnancy to that reported postpartum. Overall smoking behavior change was assessed by comparing the reported CPD category 3 months prior to pregnancy to postpartum. (Thus, overall smoking change includes women who quit and stayed quit, as well as women who quit and relapsed.) For each of the time points the following variables were defined: individuals who reported no cigarettes were designated as quit; those that reported a change to a category of CPD that reflected reduced smoking were designated as reduced; and those who reported no change in category or a change to a category of CPD that reflected increased smoking were designated as same/more. For the logistic regression analyses, the categories quit and reduced were grouped together and contrasted with same/more. 2.3. Data analysis Population adjusted proportions with 95% confidence intervals (CI) were computed using the population weight assigned to each observation in the PRAMS data set. Bivariate analysis was performed comparing pregnancies that were classified as intended/mistimed versus unwanted using the chi-square statistic for select demographic factors. Stratum-specific odds ratios were examined for homogeneity using the Breslow-Day test with a p value of less than 0.05 considered as evidence of effect modification. Next, crude odds ratios were computed via logistic regression to determine the odds of smoking behavior change by pregnancy intention. Backwards logistic regression was then manually performed adjusting for important potential confounders, using change-inestimate criteria of 10%. 3. Results
2.2. Measures 3.1. Demographic characteristics Sample inclusion criterion was limited to those respondents who reported any cigarette consumption in the 3 months prior to pregnancy, after responding in the affirmative to the screening question, “Have you smoked at least 100 cigarettes in the past 2 years?” Demographic and background characteristics collected in PRAMS included variables generated from birth certificates (e.g., pre-term or term delivery status, age, education, race/ethnicity, parity, marital status) and from questionnaire (e.g., income, health insurance, prenatal care health behaviors, and birth outcomes). Pregnancy intention was assessed by response to the following PRAMS survey question: "Thinking back to just before you got pregnant with your new baby, how did you feel about getting pregnant?" [emphasis in original]. Those who responded "I wanted to be pregnant then" or "I wanted to be pregnant sooner" were classified as intended pregnancies. Those who responded "I wanted to be pregnant later" were classified as mistimed. Those who responded "I didn't want to
The final sample consisted of 49,510 women who had a recent live birth and self-reported any cigarette smoking in the 3 months prior to pregnancy. The sample represented a population that was approximately 76% White, 12% Black, 7% Hispanic, and 5% other racial groups. Approximately 13% of the sample was less than 20 years of age, 35% ages 20–24, 29% ages 25–29, and 23% age 30 or older. Approximately 75% had at least 12 years of education and 57% were unmarried. Table 1 summarizes these demographic and other background characteristics from the weighted estimates of the sample. 3.2. Smoking behavior change by pregnancy intention Table 2 presents estimates of cigarette smoking behavior change measured at different pregnancy time points (as defined in section 2.2) and stratified by pregnancy intention (intended, mistimed,
M.S. Chisolm et al. / Journal of Substance Abuse Treatment 46 (2014) 189–193 Table 1 Demographic and background characteristics of sample. Demographic or background characteristic
% (95% CI)
Race/Hispanic origin White, non-Hispanic Black, non-Hispanic Hispanic Other, non-Hispanic Age (years) Less than 20 20–24 25–29 30 or older Education (ages 20+) Less than 12 years 12 years or higher Marital status Unmarried Married Income year prior to delivery Less than $10,000 $10,000–14,999 $15,000–24,999 $25,000–50,000 Greater than $50,000 Insurance prior to pregnancy Yes No Medicaid enrollment Yes No Timing of prenatal care (PNC) First trimester Second or third trimester Never initiated Smoking discussed in PNC Yes No Pre-term delivery Less than 37 weeks Less than 34 weeks Breastfed Ever Never
76.4 (75.8, 77.0) 11.9 (11.4, 12.4) 6.5 (6.1, 6.9) 5.3 (5.0, 5.6) 12.9 35.1 28.9 23.1
(12.4, (34.3, (28.2, (22.5,
13.5) 35.8) 29.6) 23.8)
24.2 (23.6, 24.9) 75.8 (75.1, 76.5) 57.1 (56.4, 57.9) 42.9 (42.1, 43.6) 29.5 13.2 17.2 20.7 19.5
(28.7, (12.6, (16.6, (20.1, (18.9,
30.2) 13.7) 17.8) 21.4) 20.2)
45.6 (44.9, 46.4) 54.4 (53.6, 55.1) 61.4 (60.6, 62.1) 38.6 (37.9, 39.4) 76.5 (75.8, 77.1) 22.5 (21.8, 23.1) 1.1 (0.9, 1.3) 85.4 (34.9, 86.0) 14.6 (14.1, 15.2) 10.2 (9.8, 10.6) 2.7 (2.6, 2.9) 63.4 (62.6, 64.2) 36.6 (35.8, 37.4)
and unwanted). The bulk of smoking behavior change occurred during pregnancy (from 3 months prior to pregnancy to last 3 months of pregnancy) and this change was greatest among women with either intended or mistimed pregnancies. Only 18% of women with intended pregnancies and 17% of those with mistimed pregnancies continued to smoke at the same level or greater compared to 28% of women with unwanted pregnancies (p b 0.001). However, these behavioral changes were not observed between the last 3 months of pregnancy to the postpartum period (p = 0.524). When compar-
Table 2 Cigarette smoking behavior change by pregnancy intention status. Cigarette smoking behavior change During pregnancy Quit Reduced Same/More Postpartum Quit Reduced Same/More Overall Quit Reduced Same/More
Intended (%)
Mistimed (%)
Unwanted (%)
p value
49.4 32.6 18.0
44.7 38.0 17.3
33.9 38.2 28.0
b0.001
5.1 5.3 89.7
4.5 5.4 90.1
4.6 6.2 89.2
0.524
28.8 23.8 47.4
22.1 27.1 50.8
17.3 23.7 59.0
b0.001
191
ing smoking behavior across the entire course of pregnancy (from 3 months prior to pregnancy to postpartum), 10% fewer women with intended or mistimed pregnancies smoked at the same level as they did prior to pregnancy compared to women with unwanted pregnancies (47.4 or 50.8 vs. 59.0%) (p b 0.001). Of note, the “reduced” change status demonstrated the least change across pregnancy time points and by pregnancy intention groups compared with either “quit” or “same/more.” Table 3 presents the crude and adjusted odds ratios of smoking behavior change by pregnancy intention status. For the purpose of this analysis, overall smoking change was used (i.e., smoking change from 3 months prior to pregnancy to postpartum). Women with unwanted pregnancies had 0.67 times the odds of quitting or reducing smoking compared to women with intended/mistimed pregnancies (95% CI: 0.61, 0.73). After adjusting for confounders, the odds shifted towards the null value but remained significant (0.86 [95%CI: 0.78, 0.95]). Controlling for other factors in the model, women with at least a high school education had a greater likelihood of quitting or reducing compared to women with less education. In contrast, women with Medicaid, as well as those with a prior birth, had a lower likelihood of quitting or reducing. Compared with White Non-Hispanic women, Black Non-Hispanic women had a lower likelihood of quitting or reducing smoking whereas other racial/ethnic groups had a higher likelihood.
4. Discussion 4.1. Conclusions To the authors’ knowledge, this is the first study to look at how pregnancy intention modifies change in cigarette smoking behavior throughout the perinatal time period. Using a nationally representative sample revealed that women with unwanted pregnancies were less likely to quit or reduce cigarette smoking compared with women with intended or mistimed pregnancies. Additionally we found that among women who reported smoking in the 3 months prior to pregnancy, the bulk of behavior change happened relatively early in pregnancy, before the final 3 months. Our findings are consistent with those of previous studies showing that women with intended pregnancies are more likely to engage in health-promoting behaviors, such as adherence to prenatal care
Table 3 Weighted estimates of odds ratios for cigarette smoking behavior change by pregnancy intention status (unwanted vs. intended/mistimed pregnancies). OR (95% CI) Crude odds ratio Unwanted pregnancy Adjusted odds ratio Unwanted pregnancy Parous - prior birth Medicaid High school education Race Black/NHa compared with White/NH Hispanic compared with White/NH Other/NH compared with White/NH Income Less than $10,000/year compared with more than $50,000/year $10–14,000/year compared with more than $50,000/year $15–24,000/year compared with more than $50,000/year $25–50,000/year compared with more than $50,000/year Age Less than 20 years compared with 30 years or older 20–24 compared with 30 years or older 25–29 compared with 30 years or older a
NH = Non-Hispanic.
0.67 (0.61, 0.73) 0.86 0.48 0.89 1.38
(0.78, (0.44, (0.81, (1.26,
0.95) 0.54) 0.97) 1.51)
0.76 (0.68, 0.85) 1.49 (1.29, 1.73) 1.20 (1.04, 1.38) 0.73 0.73 0.75 0.81
(0.64, (0.63, (0.66, (0.72,
0.84) 0.84) 0.86) 0.91)
0.68 (0.59, 0.78) 0.81 (0.74, 0.90) 1.05 (0.96, 1.15)
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appointments, good nutrition, and smoking cessation, compared to women with unwanted pregnancies (Altfeld et al., 1997; Cheng et al., 2009; Chuang et al., 2010; Dott et al., 2010; Kost et al., 1998; Orr et al., 2008). However these findings add to current knowledge by documenting minimal variability between the pregnancy intention categories of intended and mistimed. For example, overall rates of quitting or cutting back were not significantly different during pregnancy and postpartum between women with intended versus mistimed pregnancies but were different when compared with unwanted pregnancies. In other words, a pregnancy classified as unwanted has a stronger negative impact on changing unhealthy smoking behavior than intended or mistimed pregnancies. The results indicate that approximately 5–6% of women reported quitting or reducing cigarette smoking during the postpartum period, regardless of pregnancy intention status. The postpartum period is not typically associated with smoking reduction/cessation and, in fact, is associated with a high prevalence of smoking relapse (Ebrahim & Gfroerer, 2003). However, for some women, the postpartum appears to be a time of healthy change and so offer another window of opportunity in which providers can encourage women, with intended, mistimed, and unwanted pregnancies, to quit or reduce smoking. 4.2. Strengths and limitations This study has several important strengths, including in-depth analyses of pregnancy intention and perinatal cigarette smoking behavior change data collected from a large nationally representative sample. Furthermore, the study examined three categories of pregnancy intention (intended, mistimed, and unwanted) and assessed specific types of cigarette smoking behavior change (quit smoking, reduced smoking, and smoking more or no change) at three perinatal time intervals (during pregnancy, postpartum, and overall). Despite these strengths, there are several limitations to be considered when evaluating the study findings. First, pregnancy intention status and CPD are both based on self report, which for cigarette smoking most likely represents an under-estimation of the true prevalence of perinatal cigarette smoking behavior (Burstyn et al., 2009). Second, the questionnaire is retrospectively completed by postpartum women recalling behaviors, health care use, and morbidities that occurred before, during, and after pregnancy, thus increasing the likelihood of recall bias and other inaccuracies. Third, the phase 5 PRAMS questionnaire does not specifically ask women when they became aware of being pregnant, leaving the definition of pre-pregnancy open to interpretation, which may result in over-reporting of smoking cessation and reduction during the first 3 months of pregnancy. For that reason, future phases of PRAMS will include a question about timing of pregnancy awareness. Fourth, PRAMS data are collected only from women who deliver live births, thus the data are not generalizable to women who have still births or miscarriages, which may result in under-sampling of adverse pregnancy outcomes, particularly stillbirth, which is associated with perinatal cigarette smoking. Finally, the overall smoking behavior change measure included women who quit and stayed quit, as well as those who quit and relapsed, and these two behaviors may be operating differently by pregnancy intention status. In conclusion, this is the first study to provide estimates of cigarette smoking behavior change among U.S. women across three categories of pregnancy intention and three perinatal time intervals. Perinatal cigarette smoking and unwanted pregnancies are both highly prevalent public health problems in the U.S. Half of pregnancies in the US are unplanned and only half of all women who smoke cigarettes are able to quit during pregnancy. Viewing cigarette smoking and pregnancy intention through a health behavior lens may help treatment providers discover clues to solving both of these highly prevalent and problematic behaviors. In the meantime,
smoking cessation interventions timed to pre- and early pregnancy care appear more likely to lead to reduction or cessation in cigarette smoking, regardless of pregnancy intention, although change may be more difficult among women with unwanted pregnancies.
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