Effects of interpregnancy interval and outcome of the preceding pregnancy on pregnancy outcomes in Matlab, Bangladesh

Objective To estimate the effects on pregnancy outcomes of the duration of the preceding interpregnancy interval (IPI) and type of pregnancy outcome that began the interval. Design Observational population -based study. Setting The Maternal Child Health-Family Planning (MCH-FP) area of Matlab, Bangladesh. Population A total of 66 759 pregnancy outcomes that occurred between 1982 and 2002. Methods Bivariate tabulations and multinornial logistic regression analysis. Main outcome measures Pregnancy outcomes (live birth, stillbirth, miscarriage [spontaneous fetal loss prior to 28 weeks], and induced abortion). Results When socio-economic and demographic covariates are controlled, of the IPIs that began with a live birth, those <6 months in duration were associated with a 7.5-fold increase in the odds of an induced abortion (95% Cl 6.0-9.4), a 3.3-fold increase in the odds of a miscarriage (95% Cl 2.8-3.9), and a 1.6-fold increase in the odds of a stillbirth (95% Cl 1.2-2.1) compared with 27- to 50-month IPIs. IPIs of 6-14 months were associated with increased odds of induced abortion (2.0, 95% Cl 1.5-2.6). IPIs >= 75 months were associated with increased odds of all three types of non-live-birth (NLB) outcomes but were not as risky as very short intervals. IPIs that began with a NLB were generally more likely to end with the same type of NLB. Conclusions Women whose pregnancies are between 15 and 75 months after a preceding pregnancy outcome (regardless of its type) have a lower likelihood of fetal loss than those with shorter or longer IPIs. Those with a preceding NLB outcome deserve special attention in counselling and monitoring.