Immunoreactive Corticotropin-Releasing Hormone in Human Plasma During Pregnancy, Labor, and Delivery*

We previously reported that immunoreactive corticotropin-releasing hormone (CRH) is present in human placenta and third trimester maternal plasma, and that such material is very similar to rat CRH and the predicted structure of human CRH. We suggested that maternal plasma immunoreactive CRH may be of placental origin. To further investigate this possibility, we measured plasma immunoreactive CRH in women during pregnancy, labor, and delivery and 1 and 2 h postpartum, and in nonpregnant women. Umbilical cord plasma and placental CRH concentrations were also measured. In the first trimester of pregnancy, the mean maternal plasma level was 5.9 ± 1.0 pg (±sem)/ml (n = 24), not significantly different from that in 10 nonpregnant women (5.8 ± 0.8 pg/ml). Plasma CRH concentrations progressively increased during pregnancy (second trimester, 35.4 ± 5.9 pg/ml (n = 39); early third trimester (28–34 weeks), 263 ± 41 pg/ml (n = 14); late third trimester (35-40 weeks), 800 ± 163 pg/ml (n = 20)]. There was a significant...