Adverse Impact of Maternal Cigarette Smoking on Preterm Infants: A Population-Based Cohort Study

Objective The aim of the study is to examine the impact of exposure to maternal cigarette smoking on neonatal outcomes of very preterm infants. Study Design A retrospective cohort study examined preterm infants (< 33 weeks gestational age) admitted to the Canadian Neonatal Network centers between 2003 and 2011. Mortality and major morbidities (bronchopulmonary dysplasia, severe intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy) were compared between infants exposed and unexposed to maternal smoking during pregnancy after adjusting for confounders. Results Among 29,051 study infants, 4,053 (14%) were exposed to maternal smoking during pregnancy. Multivariable analysis revealed higher odds of grade 3 or 4 intraventricular hemorrhage or periventricular leukomalacia (adjusted odds ratio [OR]: 1.21, 95% confidence interval [CI]: 1.04-1.41) and bronchopulmonary dysplasia (adjusted OR: 1.16, 95% CI: 1.02-1.33) in the smoking group, while mortality, severe retinopathy, and necrotizing enterocolitis were not significantly different. Conclusion Maternal smoking during pregnancy is associated with severe neurological injury and bronchopulmonary dysplasia in preterm infants.