| Abstract: | Maternal smoking during pregnancy has been shown to be associated with reduced birthweight and increased fetal and infant mortality. This paper examines these patterns in first and second maternally-linked singleton pregnancies from 1978 to 1990 among 176 843 Missouri resident women with known smoking status in both pregnancies. Generally women were more likely to smoke in their second pregnancies (27.4%), than in their first (25.8%). This pattern was strongest among those whose first pregnancies occurred as teenagers, and for black women. The relationships of smoking during the first and second preg-nancies to outcomes in the second pregnancies were examined primarily through multivariate logistic regression. The adjusted relative risk (RR) of low birthweight (<2500 g) in the second pregnancy to not smoking in either pregnancy was 1.82 for those who smoked during the second pregnancy only, and 1.87 for those who smoked in both pregnancies. For those who smoked in the first pregnancy only, the RR was 0.97, not significantly different from 1. Adjusted smoking RRs for small-for-gestational age were larger, while adjusted RRs for fetal and neonatal mortality were smaller than the smoking RRs for low birthweight. |
