Metabolic and hormonal effects of antenatal betamethasone after 35 weeks of gestation

Antenatal corticosteroid therapy recently has been considered for term and near-term infants, in addition to preterm infants, delivered by elective cesarean section, with the aim of preventing an adverse respiratory outcome.

The objective of this study was to investigate hormonal and metabolic effects of antenatal betamethasone when administered to term fetuses.

Cord blood levels of cortisol, C-peptide, insulin-like growth factor I and its binding protein 3, and 5 more analytes including glucose were measured in singleton newborns of over 35 weeks of gestational age. In anticipation of a cesarean delivery, the mother was either treated or not treated with 12 mg of intramuscularly administered antenatal betamethasone approximately 24 hours prior to birth. Babies of comparable gestational age, sex, and nutritional status who were not treated antenatally served as controls.

Cord serum cortisol levels of the betamethasone-treated fetuses were suppressed to <10% of that of untreated controls (median levels of 11.6 nmol/L vs. 138.2 nmol/L, respectively), and their C-peptide and glucose levels were significantly higher (2.85 mcg/L vs. 1.19 mcg/L, respectively, p < 0.0001; and 62.5 mg/dL vs. 56.0 mg/dL, respectively, p = 0.01).

Prophylactic betamethasone therapy causes immediate hormonal alterations, which might interfere with the metabolic adaptation of the newborn. This issue deserves thorough investigation.