Objective: To evaluate the relationship between maternal smoking and fetal congenital central nervous system malformations.
Methods: Retrospective review of all cases of fetal congenital malformations of the central nervous system (CNS) identified at or shortly after birth over a 10-year period (1986-1995) in a university teaching obstetric department.
Results: The total number of CNS abnormalities identified was 79, constituting 0.13% of all deliveries over the period (n = 59,392) and 4.7% of all congenital malformations (n = 1,678). The incidence of smoking mothers was 1.64% over the study period. Four babies had hydranencephaly, 3 of these mothers being smoking teenagers. The odds ratio of having a hydranencephalic fetus in smoking mothers compared to non-smokers was 56 (95% CI 7.41-427) in the group with CNS abnormalities, 136 (95% CI 14.5-1280) in the group including all congenital malformations, and 179 (95% CI 18.6-1719) in the group including all deliveries.
Conclusion: Maternal smoking did not appear to increase the incidence of fetal congenital CNS abnormalities overall, but might be associated with particular vascular patterns of damage to the developing brain that could predispose to a hydranencephalic malformation.