Objectives: The purpose of this study was to examine the association between previous pregnancy losses and subsequent risk of preterm delivery.
Study design: A population-based Swedish study including information on all births and women's hospital admissions for pregnancy loss (n = 601,883) in Sweden between 1987 and 2000 was performed. The risk of preterm delivery after a previous pregnancy loss was estimated using logistic regression models. The risk of preterm premature ruptures of the membranes (PROM), preterm labor, and other reasons for preterm delivery was also assessed.
Results: Previous spontaneous abortions and missed abortions were associated with increased risks of preterm delivery, and the risks increased with severity of preterm delivery. Previous pregnancy loss increased the risk of preterm PROM and preterm labor foremost in deliveries before 32 weeks, but was not associated with other reasons of very preterm delivery.
Conclusion: Our results support the hypothesis that pregnancy loss and early preterm delivery may share etiologic causes.