First-trimester vaginal bleeding and the loss of chromosomally normal and abnormal conceptions.

The frequency of first-trimester vaginal bleeding among 670 women with chromosomally normal fetal losses and 219 women with chromosomally abnormal losses was compared with that among 3089 women delivered at term. Vaginal bleeding early in gestation was predictive of pregnancy outcome in that moderate or heavy bleeding was associated with a fourfold risk of the loss of either chromosomally normal or abnormal conceptions. Spotting or slight bleeding was associated with a 2.7-fold risk of the loss of a chromosomally normal conception but was not associated with the loss of chromosomally abnormal conceptions when all abnormalities were categorized together.