Health Status of Offspring Conceived During Hydroxyurea Therapy for Sickle Cell Disease.

Abstract 1533

Poster Board I-556

Hydroxyurea (HU) is an S-phase specific cytotoxic agent (pregnancy category D), approved for use in sickle cell disease (SCD) primarily due to its ability to augment production of fetal hemoglobin (HbF), which has been shown to reduce the frequency of pain crises and decrease the need for blood transfusions. In all animal species tested, HU produced an increase in congenital anomalies. Defects of the central nervous system, palate, and skeleton occurred in rats treated with HU in the ninth to twelfth gestational days. Embyonic cytotoxicity may be secondary to formation of reactive free radicals. Because of its teratogenic potential, patients with SCD are instructed to practice contraception while on HU therapy. However, risks associated with maternal or paternal HU exposure at the time of conception is unclear. Our review of the literature has only shown six case reports of HU exposure in pregnancy for the treatment of SCD. Two of these pregnancies were terminated with medical abortion, the remaining four cases described liveborn infants with normal phenotypes at 15 to 21 months of follow up. 236 patients followed at the Medical College of Georgia Sickle Cell Center have been on HU for a period of 6 months to 14 years. Despite precautionary counseling, we have identified seven women and three men with SCD who have conceived while on HU therapy. We analyzed the birth records of ten children conceived during HU therapy. The duration of HU therapy varied from 2 weeks to 3 years at the time pregnancy was diagnosed; gestational age when HU was discontinued ranged from 3 to 10.5 weeks. Some children were born prematurely or preterm, with birth weights ranging from 922 to 3178 grams. APGAR scores ranged from 2 to 9 for the first minute and 8 to 10 for the five minute score. One child who had been born severely premature at 26 weeks with a birth weight of 922 grams and APGAR scores of 2 and 8 at one and five minutes to a father who had been on HU at the time of conception was ultimately withdrawn from life support measures. The remaining nine children were assessed for appropriate development by questionnaires provided to parents as well as pediatric records when available. One child with APGAR scores of 5 and 9 has been diagnosed with mental retardation and attention deficit disorder. Developmentally, the other eight children have achieved appropriate milestones. Women with sickle cell disease are more likely to develop complications such as intrauterine growth retardation and preterm delivery than those without the disease. These findings suggest that children conceived on HU therapy are not significantly different from other infants born to parents with SCD who are not on HU. Our sample size is not large enough to observe the potential effects of in utero HU exposure. The small number of subjects is likely secondary to potential teratogenicity discouraging women to become pregnant as well as paucity of exposed pregnancies due to menstrual disturbances induced by HU. It is therefore important to develop and maintain a national registry to allow longer follow up of exposed children and more careful assessment of fetotoxic effects for those conceived during HU therapy for SCD.