Hydroxyurea in two pregnant women with sickle cell anemia.

Hydroxyurea is classified as an S-phase antineoplastic agent (pregnancy category D). Two women became pregnant while taking hydroxyurea for sickle cell anemia and delivered live infants with no congenital anomalies. Although teratogenic effects of hydroxyurea were reported in animal studies, several case reports suggest the agent may have minimal teratogenic effects on the developing fetus. Fourteen cases of hydroxyurea therapy in pregnant patients with acute or chronic myelogenous leukemia, primary thrombocythemia, or sickle cell disease are reported in the literature. Three pregnancies were terminated by elective abortion; one woman developed eclampsia and delivered a phenotypically normal stillborn infant. All other patients delivered live, healthy infants without congenital anomalies. Further studies with larger numbers of patients receiving hydroxyurea during pregnancy, with longer follow-up of exposed children and more careful assessment of fetotoxic effects, are required before the agent can be promoted as safe in pregnancy.