Objective: To analyse how psychosocial and social factors are associated with heavy smoking in the third trimester of pregnancy.
Design: Data were collected from a prospective study primarily initiated to study fetal growth retardation. (NICHD Study of successive small for gestational age births).
Setting: Uppsala in Sweden, Bergen and Trondheim in Norway.
Subjects: Study subjects were 775 para I and II, referred from GPs or maternity wards to the University Hospitals in Uppsala, Bergen and Trondheim. All women smoked at the time of conception. "Heavy smokers" were defined as women who smoked 15 or more cigarettes per day during the third trimester.
Main outcome measure: Psychosocial factors and potentially associated heavy smoking in the third trimester.
Results: Young women and women without a partner smoked heavily more often than older women and married/cohabitant women. Growing up with just one parent and the experience of a difficult childhood were also significantly associated with heavy smoking before delivery. If the woman's family (except partner) did not approve of the pregnancy, the woman was more often a heavy smoker. The women who smoked heavily in the third trimester had started smoking at an earlier age than the rest of the smokers.
Conclusion: The pregnant woman's previous and present psychosocial conditions are related to her heavy smoking in the third trimester of pregnancy.