Antepartum haemorrhage: the influence of first trimester uterine bleeding.

The influence of first trimester uterine bleeding on the incidence of antepartum haemorrhage was evaluated in 374 patients. The incidence of abruptio placentae and placenta previa were 1.0% and 2.0% respectively in these patients. In the control group of patients who did not experience first trimester uterine bleeding, the incidence was 0.4% for abruptio placentae and 1.0% for placenta previa. The study indicates that first trimester threatened abortion is associated with about 21/2 fold risk of abruptio placenta and placenta previa than in the general obstetric population. The possible reasons for these incidences are discussed.