The natural history of smoking during pregnancy among women in Nova Scotia.

Smoking during pregnancy is a serious public health problem, with adverse effects for both mother and baby. It is estimated that 25%–40% of women smokers try to stop smoking on their own upon learning that they are pregnant, yet little information is available at a population level on smoking patterns during pregnancy. In this report we describe the prevalence of smoking among pregnant women in Nova Scotia in 1997. Information concerning all hospital births in Nova Scotia in 1997 that was routinely collected by the Nova Scotia Atlee Perinatal Database was used in our study. Standardized forms were completed prospectively by medical personnel at prenatal visits, during labour and delivery, and in the postpartum period up to the time of discharge. Information on smoking included self-reported smoking status and the mean number of cigarettes smoked per day. A total of 9808 women in Nova Scotia delivered a live infant in hospital in 1997. The figures reported here concern 8528 women whose smoking status before their pregnancy is known. The overall rate of smoking before pregnancy (n = 2822) was 33.1% (95% confidence interval [95% CI] 32.1%–34.1%). Fig. 1 presents the changes in smoking status that occurred from before pregnancy to the first prenatal visit, and then to the time of admission for delivery. Of the 2822 women who were smokers before their pregnancy, 1973 (69.9%) remained smokers throughout their pregnancy (95% CI 68.2%–71.6%). Another 8.4% (237/2822) were The natural history of smoking during pregnancy among women in Nova Scotia