Maternal smoking during pregnancy and child overweight: systematic review and meta-analysis

Abstract

Objective: Perform a systematic review of studies reporting on the association between maternal prenatal cigarette smoking and child overweight. Design: Meta-analysis of observational studies. Data sources: Medline search and review of reference lists among studies published through June 2006. Review methods: Included studies reported an association between maternal smoking during pregnancy and risk of overweight among children at least 2 years of age. We did not include in the meta-analysis studies that provided only a continuous measure of adiposity, although those studies are discussed separately. Results: Based on results of 84 563 children reported in 14 observational studies, children whose mothers smoked during pregnancy were at elevated risk for overweight (pooled adjusted odds ratio (OR) 1.50, 95% CI: 1.36, 1.65) at ages 3-33 years, compared with children whose mothers did not smoke during pregnancy. The pooled estimate from unadjusted odds ratios (OR 1.52, 95% CI: 1.36, 1.69) was similar to the adjusted estimate, suggesting that sociodemographic and behavioral differences between smokers and nonsmokers did not explain the observed association. Although we observed evidence for publication bias, simulating a symmetric set of studies yielded a similar estimate (OR 1.40, 95% CI: 1.26, 1.55). Conclusions:Prenatal smoking exposure appears to increase rates of overweight in childhood. In parts of the world undergoing the epidemiologic transition, the continuing increase in smoking among young women could contribute to spiraling increases in rates of obesity-related health outcomes in the 21st century.

Is low birth weight in the causal pathway of the association between maternal smoking in pregnancy and higher BMI in the offspring?

“…Other recent studies, however, have suggested a role of (low) birth weight in the pathway of the association of intrauterine nicotine exposure and later overweight (4,7,8,37). Based on our data, a potential role of low birth weight for offspring's later overweight is not confined to children of smoking mothers: Although birth weight was slightly shifted towards lower values in children of smoking mothers, the mostly linear association between birth weight and later BMI was maintained.…”

“…Parents were encouraged to consult their "maternity passes" when answering the questions on gestational age and weight at birth. Recall of smoking habits has been reported to yield valid results in general (42), but the validity of self-reported smoking in pregnancy -which was also the standard method of smoking assessment in other studies (1,(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) -is doubtful, since the number of smoking mothers might be underestimated (43). However, we do not feel that this limitation should have caused substantial bias to the main results of our study: If a number of mothers who smoked during pregnancy were misclassified as non-smokers, the effect size of smoking on BMI-SDS might even have been underestimated in the overall analyses.…”

“…A number of cross-sectional and prospective studies have suggested a priming effect of maternal smoking in pregnancy on offspring's overweight (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Although the epidemiological evidence for this association is consistent, the underlying mechanisms remain largely unknown.…”

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review

“…These studies found an association between maternal prenatal smoking and childhood obesity even after accounting for various confounding factors. 12,16,76,[78][79][80][81][82][83][84][85][86][87][88][89][90][91] Although there is a compelling link between prenatal smoking and childhood obesity, it is not always clear-cut for both genders and all maternal smoking levels. 86,87 One study followed children from 2 to 10 years of age and found that males whose mothers smoked during pregnancy had a lower BMI at age 2 years than those born to non-smoking mothers or had partners who smoked.…”

Barriers and facilitators to smoking cessation in pregnancy and in the post‐partum period: The health care professionals’ perspective

“…Antenatal smoking is strongly associated with health complications including miscarriage (Pineles, Park, & Samet, 2014), stillbirth (Flenady et al ., 2011), spontaneous preterm birth, small for gestational age (Moore, Blatt, Chen, Van, & Defranco, 2016), asthma (Moshammer et al ., 2006), and childhood obesity (Oken, Levitan, & Gillman, 2008). In the United Kingdom, approximately 12% of women smoke throughout pregnancy (Health and Social Care Information Centre, 2016; The NHS Information Centre, 2011).…”