Risk of postpartum induced abortion in Finland: a register-based study.

CONTEXT Half of Finnish abortion patients already have children, and one in 10 pregnancies ending in abortions started within 12 months of a birth. Thus, many women may not practice contraception effectively during the postpartum period. METHODS Data from national registers were used to create ajoint data file on pregnancies occurring in Finland over the period 1987-1998. The abortion risk (the risk of a conception that leads to an induced abortion) and abortion ratio (the number of conceptions leading to abortions divided by the number leading to deliveries) were analyzed in follow-up periods after all live births to women younger than 45 (684,922), using hazard regression and logistic regression. RESULTS Pregnancies starting within eight months postpartum were more likely to end in abortion than were those starting later. Within the first eight months, the shorter the interval to the next pregnancy, the more likely the pregnancy was to end in abortion. Abortion risk was higher 6-18 months postpartum than at later periods and was highest at 6-8 months postpartum, particularly among unmarried women and teenagers. Between 1987-1988 and 1995-1996, the abortion risk within the first eight months postpartum rose significantly among women aged 25-29 and 30-34 (relative risks, 1.5 and 1.2, respectively). The abortion risk and abortion ratio were higher among teenagers than among women in other age-groups. CONCLUSIONS The findings are consistent with the hypothesis that contraceptive practice is less effective postpartum, suggesting room for improvement in postpartum contraceptive counseling in Finland.