Smoking behaviour among pregnant women prior to antenatal care registration.

Changes in smoking behaviour during early pregnancy and factors influencing such changes were studied in an unselected, area-based population. During 1987, all women registered at the antenatal care clinics in Uppsala county. Sweden, received a self-administered questionnaire regarding past and present smoking habits. Thirty-two per cent (n = 1160) were daily smokers at the time of conception. Almost one-fourth of the smokers (n = 263) had quit smoking at the first visit to antenatal care 6-10 weeks later. Using logistic regression analyses, we found that low education, not living with infants's father and whether others smoked at home or at work were factors that were independently associated with increased risks of smoking at time of conception as well as continued smoking in early pregnancy. Continued smoking was also significantly more common among women with previous births, women who started smoking at an early age and women who smoked heavily.