Smoking in Dutch pregnant women and birth weight.

In this study 796 ambulatory singular pregnant women were questioned about their smoking habits both before and during pregnancy (ambispective). Important covariates such as parity, blood pressure, maternal weight gain, salt- and alcohol consumption and length of gestation were taken into account. At the beginning of pregnancy 52% of the questioned women smoked; 36% smoked in the seventh/eighth month of pregnancy. A dose-response relationship was found between the number of cigarettes smoked per day and birth weight. For those pregnant women who still smoked after 7 months of pregnancy an average birth weight loss of 24 g was found per cigarette per day. Even after controlling for covariates, there still remains an independent influence of smoking on birth weight loss on the average of 19 g for each cigarette smoked per day.