Original Research
Obstetrics
Changes in e-cigarette and cigarette use during pregnancy and their association with small-for-gestational-age birth

https://doi.org/10.1016/j.ajog.2021.11.1354Get rights and content

Background

Despite increased e-cigarette use, limited research has focused on changes in e-cigarette and combustible cigarette use around pregnancy and the subsequent effects on infant health.

Objective

This study aimed to characterize changes in e-cigarette and cigarette use from before to during pregnancy and examine their associations with small-for-gestational-age birth.

Study Design

This was a secondary data analysis of 2016–2018 data of the US Pregnancy Risk Assessment Monitoring System. We analyzed women aged ≥18 years who had a recent live birth (unweighted: n=105,438; weighted: n=5,446,900). Women were grouped on the basis of their self-reported e-cigarette and/or cigarette use 3 months before pregnancy (exclusive e-cigarette users, exclusive cigarette smokers, dual users, and nonusers) and change in e-cigarette and cigarette use during pregnancy (continuing use, quitting, switching, and initiating use). Small-for-gestational-age was defined as a birthweight below the 10th percentile for infants of the same sex and gestational age. We described the distributions of women’s sociodemographic and pregnancy characteristics in both weighted and unweighted samples. We used multivariable log-binomial regression models to estimate the relative risks for the associations between changes in e-cigarette and cigarette use during pregnancy and risk of small-for-gestational-age, adjusting for significant covariates.

Results

The rates of cessation during pregnancy were the highest among exclusive e-cigarette users (weighted percentage, 80.7% [49,378/61,173]), followed by exclusive cigarette users (54.4% [421,094/773,586]) and dual users (46.4% [69,136/149,152]). Among exclusive e-cigarette users, continued users of e-cigarettes during pregnancy had a higher risk of small-for-gestational-age than nonusers (16.5% [1849/11,206]) vs 8.8% [384,338/4,371,664]; confounder-adjusted relative risk, 1.52 [95% confidence interval, 1.45–1.60]), whereas quitters of e-cigarettes had a similar risk of small-for-gestational-age with nonusers (7.7% [3730/48,587] vs 8.8% [384,338/4,371,664]; relative risk, 0.84 [95% confidence interval, 0.82–0.87]). Among exclusive cigarette users, those who completely switched to e-cigarettes during pregnancy also had a similar risk of small-for-gestational-age with nonusers (7.6% [259/3412] vs 8.8% [384,338/4,371,664]; relative risk, 0.83 [95% confidence interval, 0.73–0.93]). Among dual users before pregnancy, the risk of small-for-gestational-age decreased from 23.2% (7240/31,208) (relative risk, 2.53 [95% confidence interval, 2.47–2.58]) if continuing use to 16.9% (6617/39,142) (relative risk, 1.88 [95% confidence interval, 1.83–1.92]) if only quitting e-cigarettes or 15.1% (1254/8289) (relative risk, 1.61 [95% confidence interval, 1.52–1.70]) if only quitting cigarettes and further to 11.2% (7589/67,880) (relative risk, 1.23 [95% confidence interval, 1.20–1.25]) if both quitting e-cigarettes and cigarettes during pregnancy, compared with nonusers.

Conclusion

Among exclusive e-cigarette users, quitting e-cigarettes during pregnancy normalized the risk of small-for-gestational-age. Among exclusive cigarette users, quitting smoking or completely switching to e-cigarettes normalized small for gestational age risk. Among dual users, smoking cessation has a greater effect than quitting e-cigarettes only, although discontinuing the use of both may lead to the greatest reduction in the risk of small-for-gestational-age.

Introduction

Maternal combustible cigarette smoking during pregnancy is associated with adverse pregnancy and birth outcomes, including inadequate gestational weight gain, cesarean delivery, low birthweight, small-for-gestational-age (SGA) birth, preterm birth, birth defects, neonatal intensive care unit admission, fetal death, and inadequate breastfeeding.1,2 In addition, gestational tobacco exposure can have long-term effects on the risk of obesity, hypertension, airway hyperresponsiveness, bronchitis, and impaired lung function in offspring.3,4

A recent increase in the use of alternative nicotine delivery systems has been most notable among young populations and women.5 Electronic cigarettes (e-cigarettes) are commonly perceived to be a safer alternative than cigarettes6 and have been marketed for their harm reduction potential.5 The use of e-cigarettes (vaping) has surpassed the use of other noncigarette tobacco products (eg, cigars, hookah, and smokeless), indicating an increased interest in these products.6,7 Pregnancy is a unique opportunity for women to change their smoking or vaping behaviors, given their enhanced health motivation and social support.8 Changes in e-cigarette and cigarette use may include quitting, reducing, initiating, or switching between products. Among women who exclusively use e-cigarettes, a substantial proportion may quit vaping during pregnancy or reduce vaping frequency (eg, from daily to less frequent use).9 Because of the perceived harm reduction, some exclusive cigarette smokers may switch to e-cigarettes during pregnancy or initiate dual use with reduced cigarette smoking. Among dual users of both e-cigarettes and cigarettes, changes in product use may also occur during pregnancy, including discontinuing cigarette smoking only, discontinuing e-cigarette use only, or discontinuing both.

AJOG at a Glance

Despite increased e-cigarette use (“vaping”), limited research has focused on changes in e-cigarette and combustible cigarette use around pregnancy and the subsequent effects on infant health.

Among 105,438 US women, most e-cigarette and combustible cigarette users quit use during pregnancy. Exclusive e-cigarette users who quit vaping and exclusive cigarette users who quit or switched to electronic cigarettes (e-cigarettes) had a normalized risk of small-for-gestational-age (SGA) neonates. Among dual users, quitting smoking was of greater benefit than quitting vaping, although quitting both had the greatest reduction in the risk of SGA.

Quitting vaping and/or smoking and switching from combustible cigarettes to e-cigarettes during pregnancy seemed to reduce the risk of SGA.

The complex nature of these changes in e-cigarette and cigarette use during pregnancy and their impact on fetal growth have not yet been addressed in the literature. SGA birth refers to infants who weigh in the bottom 10th percentile for their gestational age and sex.10,11 SGA can be constitutional or represent fetal growth restriction; however, a higher rate of SGA above the population average level implicates an increased risk of compromised growth.10 Furthermore, SGA is associated with later abnormal growth and increased morbidity, including the development of obesity, diabetes mellitus and other metabolic disorders, cardiovascular diseases, and endocrinologic disorders.10 When SGA is complicated by fetal growth restriction, there are additional health concerns for cardiovascular, respiratory, and neurologic morbidities, along with a higher risk of mortality.12 Previous studies have indicated an association between cigarette smoking cessation and decreased risk of SGA.13 A recent study found that infants of mothers who exclusively vaped in the third trimester of pregnancy were more likely to be SGA, have low birthweight, and be born preterm compared with infants of nonusers.14 However, changes in e-cigarette use during pregnancy and the associated health effects, among exclusive e-cigarette users or dual users with cigarettes, remain understudied. A pioneering study found that infants of mothers who quit e-cigarette use during pregnancy weighed more at birth than infants of mothers who continuously used e-cigarettes throughout pregnancy.15

Therefore, we aimed to (1) characterize changes in maternal e-cigarette and cigarette use around the time of pregnancy among exclusive e-cigarette users, exclusive cigarette smokers, and dual users and (2) examine their associations with the risk of SGA birth.

Section snippets

Data source

We performed a secondary data analysis using the most recent phase 8 data (2016–2018) from the Pregnancy Risk Assessment Monitoring System (PRAMS). The PRAMS is a US nationally representative surveillance project performed by the Centers for Disease Control and Prevention (CDC) that collects state-specific, population-based data on maternal attitudes and experiences before and during pregnancy.16 Data sources include birth certificates and questionnaire surveys. The sample of women who have had

Characteristics of women by prepregnancy status of e-cigarette and cigarette use

During the 3 months before pregnancy, most women were nonusers (weighted percentage, 81.9%), followed by exclusive cigarette smokers (14.2%), dual users (2.7%), and exclusive e-cigarette users (1.1%). The proportion of young women was the highest among exclusive e-cigarette users and dual users (35.2% and 40.2% were ≤24 years old, respectively) (Table). Dual users had the highest proportion of non-Hispanic Whites (75.8%) and the lowest proportion of non-Hispanic African Americans (7.8%).

Principal findings

We conducted a secondary data analysis using the most recent PRAMS data (2016–2018) to assess changes in e-cigarette and cigarette use during pregnancy and their associations with the risk of SGA birth. We found that most e-cigarette and cigarette users quit use by late pregnancy. Exclusive e-cigarette users who quit e-cigarettes and exclusive cigarette smokers who quit cigarettes or completely switched to e-cigarettes had a risk of SGA comparable with the risk observed among nonusers. Among

Acknowledgments

We appreciated the Pregnancy Risk Assessment Monitoring System (PRAMS) Working Group and the Centers for Disease Control and Prevention for providing the original PRAMS dataset and technical support.

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    M.L.G. received a research grant from Pfizer and served as a member of the scientific advisory board of Johnson & Johnson. The other authors report no conflict of interest.

    This work was supported, in part, through R21 exploratory research support from the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NIH) (grant numbers R21HD091515 and 3R21HD091515-02S1 [Diversity Supplement]), Clinical and Translational Science Award Pilot Study support from the National Center for Advancing Translational Sciences of the NIH (grant number UL1TR001412); and seed funding from the Department of Pediatrics, State University of New York at Buffalo (all awarded to X.W.). M.L.G.’s work was supported by the US Food and Drug Administration (FDA) and National Cancer Institute under grant award U54CA238110. The content is solely the responsibility of the authors and does not necessarily represent the official views of the sponsors, the NIH, or the US FDA. The sponsors had no role in the writing of the manuscript or decision to submit it for publication.

    We confirm that our material is original, has not been previously published, and has not been submitted for publication elsewhere while under consideration. Some preliminary data were reported at the annual meeting of the Society for Research on Nicotine and Tobacco, held virtually, February 24, 2021.

    Cite this article as: Shittu AAT, Kumar BP, Okafor U, et al. Changes in e-cigarette and cigarette use during pregnancy and their association with small-for-gestational-age birth. Am J Obstet Gynecol 2022;226:730.e1-10.

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