Steroids in pregnancy

Abstract

Steroids constitute one of the most frequently prescribed medicines during pregnancy. Their use is the mainstay for a variety of maternal and fed indications, both in acute and chronic conditions. The pharmacokinetics of corticosteroids during pregnancy remains unclear. Significantpharmacologic alterations occur secondary to the profound changes in the renal, gastrointestinal, and cardiovascular systems during pregnancy. Certain obstetrical conditions such as preeclampsia, diabetes mellitus and multiple gestations are associated with different volumes of distribution, interactions and clearance rates of medications, adding further complexity to the therapeutic use of glucocorticoids. There is always concern that the hypothalamo-pitutary-adrenal axis of the fetus may be suppressed by maternal steroid therapy. In practice this does not occur with prednisolone, perhaps because fetoplacental unit is relatively lacking in the enzymes :o convert prednisolone to its active metabolite prednisolone and placental ll,p-ol-dehydragenase is very efficient. deactivating 87% of an injected dose of prednisolone. The maternal-fetal concentration of prdnisolone is 10:1, in comparison to hydrocortisone 6:1 and betamethasone 3:1. Antenatal corticosteroid prophylaxis was first introduced to obstetric practice in 1972 by Liggens and Howie who showed that their use could reduce incidence of respiratory distress syndrome in premature infants. Since their introduction to clinical practice, many randomized controlled studies have confirmed the positive maturational effects of antenatal corticosteroids, which result in lower incidence and severity of respiratory distress syndrome, lower incidence of intraventricular hemorrhage, and decreased mortality. Royal College of Obstetrician and Gynaecologist recommends corticosteroid for routine use at 24 to 34 weeks' gestation when preterm delivery is anticipated. Meanwhile, numbers needed to treat will be increased significantly beyond 34 weeks' gestation. Strong evidence supports the benefits of antenatal steroids starting at 24 hours and lasting at least 7 days after treatment. There is a demonstrable reduction in morbidity and mortality even when antenatal steroids are given less than 24 hours before delivery. Significant reduction in rates of RDS following antenatal corticosteroids has not been demonstrated in pregnancies complicated by maternal diabetes mellitus and in multiple gestations. However its use is recommended. Betamethasone and dexamethasone are comparable in reducing the rate of most major neonatal morbidities. Repeated courses of antenatal corticosteroids are less well studied than single courses and are controversial. There have been reported cases of isolated cleft lip with or without cleft palate and corticosteroid use. However evidence for the teratogenicity of corticosteroids in humans is limited and has resulted in inconsistent recommendations regarding their use during early pregnancy.