Pregnancy in Essential Thrombocythemia: Experience With 40 Pregnancies

Abstract

This retrospective study reviewed the course of 40 pregnancies in 16 women diagnosed as having essential thrombocythemia (ET). These women were seen at 5 hospitals in Finland in the years 1980-1995. In 10 women, thrombocytosis was identified for the first time during pregnancy. The mean age at the time ET was diagnosed was 27 years, and the median initial platelet count was 1082 x 10 9 /L. The median follow-up interval from the time of diagnosis was 6 years 6 months. Eighteen of the 40 pregnancies (45%) were complicated. Fifteen (38%) ended in miscarriage, all but 2 of them in the first trimester. Three pregnancies ending in a live birth were complicated by eclampsia or preeclampsia. In 7 women, all 11 pregnancies were uneventful. In the other 9 patients, 18 of 29 pregnancies (62%) were complicated. Only 11 of these pregnancies (38%) followed a normal course and had a good outcome. The most common complication, occurring in one third of pregnancies and comprising 72% of all complications, was spontaneous abortion. There were 2 intrauterine fetal deaths. The risk of complications did not appear to relate to either nonpregnancy-related symptoms of ET or to the platelet count before or during pregnancy. Fetal growth was normal in all but 1 of 25 second- or third-trimester pregnancies. Eleven of the 16 women had received treatment for ET. Most commonly, acetylsalicylic acid (ASA) was given in daily doses of 50 to 250 mg. Five patients were on interferon before pregnancy and 3 of them changed to ASA. Pregnancy-related complications occurred in 67% of pregnancies in untreated women. In contrast, none of 13 pregnancies in women treated before or during pregnancy were complicated. The live birth rate was 100% in treated cases and 44% without treatment, This study affirms an increased risk of pregnancy-related complications-particularly early spontaneous abortion-when the mother has ET. Low-dose ASA treatment appears to prevent complications.