Soft drug use prior to and during pregnancy: a comparison of samples over a four-year period

The extent and changing patterns of alcohol, nicotine and marihuana use in the year before pregnancy and during each trimester were examined in 190 women who had entered the Ottawa Prenatal Prospective Study in 1980-1982. The results were compared to those obtained from women who had entered the study in 1978-1979. The two samples were very similar in demographic factors. Compared to the earlier sample there was a slight decrease among the number of heavy social drinkers prior to pregnancy and a greater tendency for these women to reduce their drinking early in pregnancy. The extent of nicotine use was very similar between the two samples prior to pregnancy and in the first trimester. However, unlike the 1978-1979 samples, the proportion of heavy smokers continued to be reduced as pregnancy proceeded. Heavy marihuana use rose slightly in the recent sample both prior to and during pregnancy.