ANTENATAL GLUCOCORTICOID ADMINISTRATION INCREASES CORTICOTROPIN-RELEASING HORMONE IN MATERNAL PLASMA

Objective This study was designed to determine whether maternal cortic otrophin-releasing hormone (CRH) concentrations are altered after mate rnal betamethasone administration for fetal lung maturity in women wit h threatened preterm labour and whether these effects are dependent on gestational age. Methods Our study included 49 woolen with threatened preterm labour who received prenatal betamethasone for fetal lung mat urity between 24 and 31 weeks of gestational age and 11 women who did not. Maternal blood was taken before and after glucocorticoid administ ration or at 24 hours after initial sampling. Plasma CRH, adrenocortic otrophin (ACTH) and cortisol concentrations were determined by radioim munoassays. The women were stratified into 24-25 weeks, 26-27 weeks, 2 8-29 weeks, and 30-31 weeks completed gestation. Results At each gesta tional age, maternal cortisol concentrations decreased by approximatel y 85% after glucocorticoid administration. Overall mean cortisol value s fell from 580.0 (SD, 351.8) to 89.7 (96.6) nmol/L (n = 40, P < 0.001 ). Overall mean ACTH values decreased from 9.9 (4.7) to 5.0 (3.4) pmol /L (n = 43, P < 0.001), and the approximate 50% decrease was similar a t each gestational age. In marked contrast, overall mean CRH values in creased from 58.0 (37.0) to 87.8 (68.6) pmol/L (n = 49, P < 0.001) aft er betamethasone administration. There was no change in maternal corti sol, ACTH or CRM values over 24 hours in women who did not receive bet amethasone. Conclusions We conclude that maternal betamethasone admini stration increases maternal plasma CRH values between 24 and 31 comple ted weeks of gestation.