Effects of Coumarin Compounds on the Fetus

Thirty-six pregnancies during which coumarin compounds were administered were reviewed to determine the risks these drugs pose to the fetus. The stage of pregnancy when treatment was begun, previous obstetric history, duration of treatment, drugs used, adequacy of control, and outcome of the pregnancy were considered. Thirty-two women delivered normal infants. Four pregnancies resulted in stillbirths. Three of these women had had previous obstetric complications, and the fourth had documented hypoprothrombinemia for 4 days before fetal movement ceased. The stage of pregnancy when therapy started and the duration of treatment were not important determinants of survival. Although occasional hypoprothrombinemia was not usually lethal, two of the four fetal deaths occurred in cases in which the prothrombin time was more than three times the control time at least on two occasions. All women with a normal obstetric history and adequate control of the prothrombin time delivered normal infants.