Fetal lung maturation, betamethasone

In children, a leukemoid reaction has been induced by betamethasone treatment (135) this possibility must always be borne in mind, since glucocorticoids can actually be used to treat leukemia or its complications. A case of very high white blood cell count with neutrophilia in a preterm infant whose mother had received two doses of betamethasone prenatally to enhance fetal lung maturation is one of a short list of leukemoid reactions possibly attributable to antenatal glucocorticoid treatment (136). 

Prenatal glucocorticoid therapy to enhance fetal lung maturation reduces neonatal morbidity and mortality. However, adverse effects of serial courses of betamethasone on mother and fetus can occur. 

Maternal hyperadrenalism occurred after five courses of betamethasone to enhance fetal lung maturation (374). 

Lung maturation in the fetus is regulated by the fetal secretion of cortisol. Treatment of the mother with large doses of glucocorticoid reduces the incidence of respiratory distress syndrome in infants delivered prematurely. When delivery is anticipated before 34 weeks of gestation, intramuscular betamethasone, 12 mg, followed by an additional dose of 12 mg 18-24 hours later, is commonly used. Betamethasone is chosen because maternal protein binding and placental metabolism of this corticosteroid is less than that of cortisol, allowing increased transfer across the placenta to the fetus. 

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