The effect of cigarette smoking during pregnancy on mode of delivery in uncomplicated term singleton pregnancies.

OBJECTIVE

To examine the influence of cigarette smoking during pregnancy on mode of delivery.

METHODS

A retrospective analysis of 6105 uncomplicated term singleton pregnancies for mode of delivery was performed with respect to smoking status.

RESULTS

Of all, 680 (84.0%) smokers and 4588 (86.7%) non-smokers had a spontaneous vaginal delivery, 65 (8.0%) smokers and 393 (7.4%) non-smokers had an instrumental delivery and 65 (8.0%) smokers and 314 (5.9%) non-smokers had a cesarean delivery (p = 0.051). Smoking during pregnancy increased the risk of any operative or instrumental intervention by OR 1.240, 95% CI 1.012-1.523. Non-reassuring fetal heart rate pattern that warranted either cesarean or instrumental intervention was present in 99 (12.2%) out of 810 smokers and in 392 out of 5295 (7.4%) non-smokers, p < 0.001). Smoking during pregnancy increased the risk of non-reassuring fetal heart rate pattern that warranted either cesarean or instrumental intervention by OR 1.650 (95% CI 1.341-2.022).

CONCLUSION

Women with uncomplicated term singleton pregnancies who smoke during pregnancy are at an increased risk of fetal compromise during labor (as judged by non-reassuring fetal heart rate pattern), leading to increased rates of operative delivery (cesarean either instrumental).