Antenatal glucocorticoids reduce growth in appropriately grown and growth-restricted ovine fetuses in a sex-specific manner

Antenatal glucocorticoids are administered to mature the fetal lungs before preterm birth. Glucocorticoids also have non-pulmonary effects, including reducing fetal body and brain growth. The present study examined whether glucocorticoid administration has a sex-specific effect on growth in appropriately grown (control) and intrauterine growth-restricted (IUGR) fetal sheep. IUGR was induced at 0.7 gestation in fetal sheep by single umbilical artery ligation. On Days 5 and 6 after surgery, IUGR or control fetuses were exposed to the synthetic glucocorticoid betamethasone (BM; 11.4mg) or saline via intramuscular maternal administration. On Day 7, a postmortem was conducted to determine fetal sex and weight. Compared with control fetuses, the birthweight of male and female IUGR fetuses was significantly reduced (by 18.5+/-4.4 (P=0.002) and 21.7+/-6.0 (P=0.001), respectively). Maternal administration of BM significantly reduced bodyweight in both control and IUGR fetuses (by 11.3+/-2.8 and 20.5+/-3.6 in control male and female fetuses, respectively; and by 22.9+/-3.1 and 38.3+/-3.4 in IUGR male and female fetuses, respectively; P