The pregnancy outcome of 347 patients with a confirmed, viable intrauterine pregnancy between 6.0 and 14.0 weeks, menstrual age, was determined. The miscarriage rate was 4.2% in a subgroup of patients without vaginal bleeding, as compared with 12.7% in a subgroup with bleeding (chi 2 = 7.4, p less than 0.006). First trimester vaginal bleeding was a significant covariate in the determination of the spontaneous miscarriage rate after fetal cardiac activity has been confirmed.