Prenatal smoking and risk of intrapartum stillbirth.

The purpose of this study was to examine the association between prenatal smoking and intrapartum stillbirth by the use of a cohort of singleton births in Missouri from 1978 through 1997. Overall, the authors identified a total of 7,325 counts of stillbirth, yielding a stillbirth rate of 4.4 per 1,000. The timing of the occurrence of the stillbirth to onset of labor was specified in 85.6% (n = 6,273). Of these, 1,070 (17.0%) occurred intrapartum. Smoking mothers were 50% more likely to experience intrapartum fetal death as compared with nonsmoking gravidas (adjusted hazard ratio = 1.5; 95% confidence interval = 1.3-1.7). Women who smoked 10 to 19 cigarettes per day were at the highest risk of experiencing intrapartum stillbirth (adjusted hazard ratio = 1.7 [95% confidence interval = 1.4-2.0]). Our findings underscore the need for increased smoking-cessation education efforts targeted toward pregnant women.