Smoking and respiratory conditions in pregnancy: associations with adverse pregnancy outcomes

Acute and chronic respiratory conditions affect a large segment of pregnant women. The purpose of the current study was to examine the concomitant effects of respiratory conditions and smoking during pregnancy on gestational age, birth weight, fetal distress, infant mortality, premature rupture of membranes, placenta abruption, and mode of delivery.

This study used data (n = 1,064,969) from the North Carolina linked birth/infant death files from 1999 to 2007. Logistic regression was used to compute odds ratios and 95% confidence intervals (CIs) in assessing risk of adverse pregnancy outcomes.

We found that women with respiratory conditions/smoking status were significantly more likely than nonsmokers with no respiratory conditions to have a low-birth-weight infant, an infant with fetal distress, and experience preterm birth and an infant's death. Adjusted odds ratios also revealed that smokers with respiratory conditions were 2.37 (95% CI 1.69-3.32) times more likely than women with no respiratory conditions/nonsmoking status to have placenta abruption and 2.20 (95% CI 1.85-2.61) times more likely to have premature rupture of membranes. Regardless of smoking status, women with respiratory conditions were less likely to have a vaginal delivery.

These findings underscore the need for clinical and public health programs to educate women, particularly those with respiratory diseases, of the immense array of adverse outcomes that may occur as a consequence of active maternal smoking during gestation. It is important for interventions to target mothers with respiratory conditions early on to ensure favorable birth outcomes.