Objective: Our purpose was to evaluate the association between spontaneous abortion and subsequent adverse birth outcomes.
Study design: Washington State birth certificate records for 1984 to 1987 were used to examine the association between spontaneous abortion and adverse outcomes in the subsequent live birth. Adverse birth outcomes were examined for women with one spontaneous abortion before the index pregnancy (n = 2146) and for women with three or more prior spontaneous abortions and no other prior pregnancies (n = 638); compared with women with no prior spontaneous abortions (n = 3099). Logistic regression was used to estimate the relative risk associated with prior spontaneous abortion of each adverse outcome.
Results: Women with three or more prior spontaneous abortions were at higher risk for delivery at less than 37 weeks' gestation (relative risk 1.5, 95% confidence interval 1.1 to 2.1), placenta previa (relative risk 6.0, 95% confidence interval 1.6 to 22.2), having membranes ruptured greater than 24 hours (relative risk 1.8, 95% confidence interval 1.2 to 2.9), breech presentation (relative risk 2.4, 95% confidence interval 1.6 to 3.6), and having an infant with a congenital malformation (relative risk 1.8, 95% confidence interval 1.1 to 3.0).
Conclusion: These findings suggest that common causes may underlie recurrent spontaneous abortion and certain adverse birth outcomes. They may also help guide clinical management of pregnancies in women with a history of recurrent spontaneous abortions.