Prior Gestational Age and Subsequent Risk for Preterm Birth among Washington State Women

Preterm birth (before 37 completed weeks of gestation) is a leading cause of infant mortality and morbidity. In this report, we explored rates of preterm birth as they relate to gestational age of prior deliveries and interpregnancy intervals (IPI) among Washington State women. We found that both prior preterm birth and early term birth were associated with subsequent preterm birth. The association between a short IPI (less than six months) and very preterm birth varied by gestational age of prior delivery. Specifically, women with a prior preterm or early term birth and a short IPI had the highest risk of subsequent very preterm birth.