Epidemiologic association between maternal smoking during pregnancy and intracranial hemorrhage in preterm infants.

The objective of this study was to evaluate the effect of maternal smoking during pregnancy on the risk of intracranial hemorrhage in preterm infants (born at 24 to 33 weeks of gestation). We conducted a case-control study of 96 preterm infants with intracranial hemorrhage and 96 gestational age-matched control subjects with negative cranial ultrasonographic findings. In conditional multiple logistic regression models, heavy maternal smoking ( > 10 cigarettes per day) during the latter half of pregnancy was associated with an increased risk of mild (grade I or II) intracranial hemorrhage (odds ratio = 5.96, 95% confidence interval 1.72 to 20.76; p = 0.005). After adjustment for the confounding effect of birth weight and respiratory distress syndrome, the risk of any intracranial hemorrhage (grade I to IV) was three times higher (adjusted odds ratio = 3.63, 95% confidence interval 1.37 to 9.63; p = 0.009) in infants of heavy smokers ( > 10 cigarettes per day) than in control subjects. The results of this study indicate that cigarette smoking during the latter half of pregnancy increases the risk of intracranial hemorrhage in preterm infants. The deleterious effect of smoking was greater for mild hemorrhages (grade I or II) and was confined to infants of heavy smokers.