A prospective study of spontaneous fetal losses after induced abortions.

The incidence of spontaneous abortions was observed among 31,917 women followed from their first prenatal visit. Life-table analysis showed that losses in the first trimester were not significantly affected by previous induced abortions, nor was any change in the risk of second-trimester losses detected among the 1493 parous women who reported having had induced abortions after childbirth. There was, however, an increase in the incidence of midtrimester losses among the 2019 nulliparous women with previous induced abortions; the age-adjusted rate of loss was 59.9 per 100,000 women at risk per day, as compared with 24.2 among the 12,042 control nulliparous women (P less than 0.001). The relative risk increased with the number of previous induced abortions and was not explained by the distribution of demographic and social variables. The risk decreased from 3.27 (95 per cent confidence limits, 1.72 to 6.23) after abortions induced before 1973, mainly by dilation and curettage, to 1.42 (0.76 to 2.65) after those done since 1973, when the more gentle technic of cervical dilation by use of laminaria was introduced. These findings indicate that there is little or no risk of spontaneous abortions after induced abortions when performed by current technics.