Changes in smoking and alcohol consumption during pregnancy: a population-based study in a rural area.

Changes in smoking and drinking behavior during pregnancy and factors influencing these changes were studied in a typical rural county. Using birth certificates and mailed questionnaires, information was obtained from 255 married women residents of Callaway County, Missouri, who gave birth in a one-year period. The women were much more likely to drink alcohol than to smoke before pregnancy (48.6 versus 28.2%, P less than .01). There was a significant decrease in both smoking and drinking during pregnancy, though the women were much more likely to modify drinking behavior than smoking behavior. Of the women who drank alcohol before pregnancy, 53.2% stopped alcohol consumption completely during pregnancy, while only 16.7% of smokers stopped smoking during pregnancy (P less than .001). Women cited fear for the infant's health as an important factor underlying the decision to decrease these behaviors more often than they did advice from doctor, family, friends, or media, or adverse physical effects of tobacco or alcohol. It was very difficult to predict changes in smoking and drinking behavior during pregnancy on the basis of demographic and behavioral characteristics such as age, income, education, attendance of childbirth classes, desirability of pregnancy, and method of infant feeding.