PLACENTAL CORTICOTROPIN-RELEASING HORMONE AND THE HYPERCORTISOLISM OF PREGNANCY

OBJECTIVE: Our purpose was to clarify whether placental corticotropin-releasing hormone regulates pituitary-adrenal function in human pregnancy. STUDY DESIGN: We examined the relationship between maternal plasma corticotropin-releasing hormone concentrations and levels of pituitary-adrenal hormones at 5-week intervals in 21 uncomplicated term pregnancies. RESULTS: Maternal plasma corticotropin-releasing hormone concentrations rose significantly from 115 +/- 45 pg/ml at 11 to 15 weeks to 4346 +/- 754 pg/ml at 36 to 40 weeks (p < 0.001). Afternoon plasma corticotropin concentrations also rose significantly from 8.8 +/- 2.8 pg/ml to 18 +/- 2.6 pg/ml (p < 0.005). Urinary free cortisol concentrations rose from 54.8 +/- 7.3 mu g per 24-hours to 111 +/- 8.7 mu g per 24 hours (p < 0.005). Maternal dehydroepiandrosterone sulfate levels fell from 102 +/- 14 mu g/dl to 63.8 +/- 7.1 mu g/dl (p < 0.005). Maternal plasma corticotropin-releasing hormone was significantly correlated with afternoon plasma corticotropin concentrations (r = 0.6, p < 0.0001) and with urinary free cortisol concentrations (r = 0.04, p < 0.01). CONCLUSIONS: Similar modest elevations of corticotropin and cortisol, as occur in pregnancy, have been reported in vitro and in vivo studies of long-term administration of corticotropin-releasing hormone. Our findings support the concept that placental corticotropin-releasing hormone modulates pituitary-adrenal function in pregnancy.