Maternal smoking in pregnancy and birth defects: a systematic review based on 173 687 malformed cases and 11.7 million controls

Abstract

BACKGROUNDThere is uncertainty over whether maternal smoking is associated with birth defects. We conducted the first ever comprehensive systematic review to establish which specific malformations are associated with smoking.METHODSObservational studies published 1959–2010 were identified (Medline), and included if they reported the odds ratio (OR) for having a non-chromosomal birth defect among women who smoked during pregnancy compared with non-smokers. ORs adjusted for potential confounders were extracted (e.g. maternal age and alcohol), otherwise unadjusted estimates were used. One hundred and seventy-two articles were used in the meta-analyses: a total of 173 687 malformed cases and 11 674 332 unaffected controls.RESULTSSignificant positive associations with maternal smoking were found for: cardiovascular/heart defects [OR 1.09, 95% confidence interval (CI) 1.02–1.17]; musculoskeletal defects (OR 1.16, 95% CI 1.05–1.27); limb reduction defects (OR 1.26, 95% CI 1.15–1.39); missing/extra digits (OR 1.18, 95% CI 0.99–1.41); clubfoot (OR 1.28, 95% CI 1.10–1.47); craniosynostosis (OR 1.33, 95% CI 1.03–1.73); facial defects (OR 1.19, 95% CI 1.06–1.35); eye defects (OR 1.25, 95% CI 1.11–1.40); orofacial clefts (OR 1.28, 95% CI 1.20–1.36); gastrointestinal defects (OR 1.27, 95% CI 1.18–1.36); gastroschisis (OR 1.50, 95% CI 1.28–1.76); anal atresia (OR 1.20, 95% CI 1.06–1.36); hernia (OR 1.40, 95% CI 1.23–1.59); and undescended testes (OR 1.13, 95% CI 1.02–1.25). There was a reduced risk for hypospadias (OR 0.90, 95% CI 0.85–0.95) and skin defects (OR 0.82, 0.75–0.89). For all defects combined the OR was 1.01 (0.96–1.07), due to including defects with a reduced risk and those with no association (including chromosomal defects).CONCLUSIONSBirth defects that are positively associated with maternal smoking should now be included in public health educational materials to encourage more women to quit before or during pregnancy.

Adolescence and the next generation

“…Maternal smoking has consistently been linked to adverse birth and child outcomes ranging from poor fetal growth, low birth weight, stillbirth, sudden unexpected death in infancy and a broad range of birth defects to later childhood behavioural problems, obesity and impaired lung function 98,99 . Heavier antenatal drinking (that is, more than three standard drinks per day) is also independently predictive of poor birth outcomes.…”

Consequences and Possible Predictors of Health-damaging Behaviors and Mental Health Problems in Pregnancy – A Review

“…Intrauterine growth disorders [21], congenital anomalies [22], low birth weight, and the risk of sudden infant death syndrome [23] have also been linked to prenatal exposure to nicotine. Over the longer term maternal nicotine consumption during pregnancy is associated with an increased risk of health problems in later life, for example, cardiac and respiratory disease or overweight [16] but also with behavioral disorders (particularly ADHD and aggressive behavior) [24,25] and cognitive deficits [26] during the childʼs further development.…”

Smoking Among Pregnant Women in Outpatient Treatment for Opioid Dependence: A Qualitative Inquiry

“…Smoking during pregnancy increases the risk of multiple adverse outcomes including ectopic pregnancy, premature birth, orofacial clefts, 1 and sudden infant death syndrome. 2 The dangers of maternal smoking continue beyond pregnancy.…”