Smoking and preterm labor.

The aim of the present study was to investigate the role of maternal smoking during pregnancy in the occurrence of the premature rupture of the membranes (PROM) and premature labor . Our study consisted of 1,133 women of which 283 (group A) had premature labor (gestation < or = 37 weeks), while 850 (group B) had term labor (gestation > 37 weeks). The two groups did not differ in their socioeconomic status and did not include women with serious complications during pregnancy. There were no apparent effects of smoking on the length of gestation. However, our results showed that smoking had a marked effect on preterm labor of less than 32 weeks; we also found a statistically significant correlation between PROM in premature deliveries and smoking during pregnancy, but no gradient was observed between the number of cigarettes smoked per day and the risk for PROM, in cases of premature labor. We conclude that smoking during pregnancy raises the risk of delivery before the 32nd week, as well as the PROM in premature deliveries, independently of the number of cigarettes smoked per day.