Folic Acid Supplementation and Twin Pregnancy in Patients with Sickle Cell Disease.

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Patients with sickle cell disease (SCD) usually take 1mg of folic acid daily. The rationale for this approach is to maintain effective erythropoiesis with a stable hemoglobin level. Other potential advantages of folate therapy in patients with SCD include the prevention of hyperhomocysteinemia that may predispose to thrombotic events, which, in turn, may lead to painful episodes. Moreover, folate supplementation during pregnancy is known to prevent neural tube defects in infants. The major disadvantage of folate supplementation in patients with SCD is that it may mask vitamin B12 deficiency. Another controversial effect of folic acid supplementation pertains to its potential effect on the number of twins coming to term. We reviewed our database on patients with SCD to determine the effect, if any, of folic acid supplementation on twin pregnancies. The data were collected prospectively since 1981. All patients routinely took 1.0 mg of folic acid orally on a daily basis. Random testing of the level of folic acid in the steady state in women with SCD including those who became pregnant showed increased levels to > 20ng/ml (Normal range: 3.0–18.0 ng/ml) in most patients. Pregnant patients also took additional perinatal vitamins that also contained folic acid. We selected those pregnant patients in whom the outcome of pregnancy was either a liveborn or stillborn at or after 20 weeks' gestation. We found that 46 patients with SCD became pregnant 60 times between 1981 and 2002 and who met the defined criteria mentioned above. The average maternal age at delivery was 26 years. Fifty-six pregnancies (93%) ended in liveborn and the remaining four (7%) in intrauterine fetal death. Five pregnancies (8.3%) resulted in the delivery of twins. This is a significantly higher rate of multiple births compared to other pregnant women. The reported rate of multiple births is between 0.34 and 1.1% both in Black and Caucasian women respectively. All twin births were dizygotic in nature. Patients with SCD take higher amounts of folic acid on a regular basis for a longer period of time before and after pregnancy than other pregnant women. This may explain why twin pregnancies are higher in these patients. The reason why folate therapy is associated with twinning is unknown at the present. Further studies may clarify the pathogenetic pathway of this phenomenon.