Predictive value of early embryonic cardiac activity for pregnancy outcome

Abstract

The biologic variation of the embryonic heart rate was investigated by transvaginal ultrasonography during the first trimester of normal (n = 141) and abnormal (n = 29) pregnancies, and the predictive value of a repeatedly diagnosed slow heart rate for pregnancy outcome was determined. The mean heart rate increased from 82 +/- 10.3 beats/min at 5 weeks' gestation to 156 +/- 9.6 beats/min at 9 weeks. A single observation of an abnormally slow heart rate did not necessarily predict subsequent embryonic death. However, a continued decline in embryonic heart activity, observed within a few days' interval, was always associated with a first-trimester abortion.