[Influence of short interpregnancy interval on pregnancy outcomes]

Optimal interpregnancy interval (IPI) is an important issue affecting pregnancy results, fetal and maternal morbidity/mortality, and has economic, social and demographic significance. The definition of IPI has not yet been standardized, thereby affecting results and conclusions. It was found that pregnancies conceived 18 to 23 months after previous birth had the lowest risks of fetal complications--low birth weight, preterm birth, and small size for gestational age. Women with shorter IPI have higher risk of maternal mortality, hypertensive disorders of pregnancy, bleeding and anemia. Studies conducted in developing countries suggest longer IPI-3 to 5 years as the optimal IPI. The relation between short interpregnancy intervals and adverse perinatal outcomes has been attributed to maternal nutritional depletion, the competition theory and behavioral risk factors. It was proposed that there is a J-shaped association between IPI and adverse pregnancy outcomes. This is not the effect of other common reproductive risk factors. There is a need to inform women regarding the association between adverse pregnancy outcomes and interpregnancy intervals, as well as the benefits of optimizing that interval. Public health programs could identify women with other risk factors (for example substance abuse, such as tobacco or alcohol, or a young/advanced maternal age) for interventions to improve perinatal outcomes. There is also a need for more studies to define the optimal IPI under local conditions.