As many as 2% of all pregnant women undergo surgery during gestation, but there are few reports of the effects of anesthesia and surgery on fetal outcome. The present paper presents information on 287 women who had surgery during pregnancy. Surgery during early pregnancy was associated with a significant increase in the rate of spontaneous abortion compared to the rate in a control group that did not have surgery. There were no differences in the incidence of congenital abnormalities in this offspring of women who had surgery during early pregnancy. The data suggest that elective surgery be deferred during early pregnancy to minimize potential fetal loss.