The effect of ethnic origin on the rate of spontaneous late mid-trimester abortion

The effect of ethnic origin on perinatal outcome is well recognized. An effect on the rate of spontaneous abortion has not been previously documented, to our knowledge. We report the results of a retrospective survey of late mid-trimester abortions (20 to 26 weeks gestation) at Dudley Road Hospital, Birmingham, England. The aims of the study were to document the rate of spontaneous late mid-trimester abortion by ethnic origin and to define any differences in these groups, both medically and as a result of histological examination of the abortus, that might account for observed differences. Over an 18-month period, during which 6508 infants beyond 26 weeks gestation were delivered, 30 late mid-trimester spontaneous abortions occurred (13 black, 10 white, 7 Asian). Abortion rates per 1000 deliveries were 12.9 for blacks, 3.6 for whites, and 2.7 for Asians. The differences between ethnic groups were statistically significant (chi 2 = 17.4; P = .0002). The black women experiencing spontaneous mid-trimester abortion were of higher mean parity and were more likely to have undergone a previous therapeutic termination. Review of pathology reports revealed more cases of chorioamnionitis and fetal pneumonia in this group. Although these results should be interpreted with caution, a relationship clearly exists between ethnic origin and late mid-trimester loss. Further study is warranted to establish the cause.