Legal abortion and placenta previa.

Legal abortion has been postulated to be a risk factor for placenta previa in subsequent pregnancies. To examine this hypothesis, we analyzed the deliveries of 28,665 women. We identified 68 women who had had placenta previa and compared their obstetric histories with those of 68 controls randomly selected from the same group of deliveries. The crude risk ratio for women with a history of one or more legal abortions was 1.4 (95% confidence interval, 0.5 to 3.6; p greater than 0.05). Standardizing the crude risk ratio for the effects of age and gravidity reduced the risk ratio to 1.1 (95% confidence interval, 0.4 to 2.8). In this predominantly black population legal abortion does not appear to have a significant association with placenta previa in subsequent pregnancies.