Smoking or quitting during pregnancy: associations with background and future social factors.

Current and future social factors associated with smoking habits during pregnancy were assessed. Data on maternal smoking, social background and the family's development during the 21 years after delivery were gathered for a prospective longitudinal cohort study of 12,068 pregnant women and their children in Northern Finland in 1966 and for a second birth cohort of 9,362 mothers in 1985-86. The prevalence of smoking before pregnancy was 22% in the 1966 cohort (29% in 1985-86). 12% (18%) of the women continued smoking throughout their pregnancy. The following background factors were mainly associated with the mother's smoking and/or continuing during pregnancy in both cohorts when mother's age, parity, place of residence and social class were standardized: mother's age under 23, parity two or more, low social class, urban dwelling, unmarried, gainful employment and heavy smoking. The follow-up responses after 14 and 21 years, respectively, were mostly more favourable among the non-smoking mothers and those who quit smoking during pregnancy-e.g. stable family structure, child's smoking and drinking habits and application for intermediate education. Smoking throughout pregnancy or quitting of smoking late in pregnancy were associated with undesirable future development of the child and family in most of these aspects.