[Successful pregnancy and delivery during alpha-interferon therapy for essential thrombocythemia].

Essential thrombocythemia (ET) was diagnosed in a 31-year-old woman who had a miscarriage in the first trimester of her first pregnancy. Because of her wish for child, the patient was given alpha interferon (alpha-IFN) instead of hydroxyurea or aspirin to lower her platelet count to about 80 x 10(4)/microliter. She also had a miscarriage in her second pregnancy. Thereafter, the platelet count was kept at 60-70 x 10(4)/microliter by dose escalation of alpha-IFN. In the 35th week of her third pregnancy, the patient delivered a healthy baby with a normal blood count. Several small infarctions were observed in the placenta. Control of platelet count by alpha-IFN administration was effective in preventing recurrent miscarriage associated with ET, and had no adverse effect on patient fertility or fetal development.