Corticotropin-releasing-hormone levels in pregnancy-induced hypertension

High levels of corticotropin-releasing hormone (CRH) circulate in the plasma of pregnant women especially during the third trimester and even higher levels have been reported in abnormal pregnancies of various etiologies. One of these etiologies is pregnancy-induced hypertension (PIH). Objective: To measure CRH blood levels with a sensitive method in a large number of pregnant women with PIH, starting from very early stages of gestation, and to compare them with those in normal controls. Study design: Venous blood was withdrawn from, (a) 10 healthy women aged 20-35 years, (b) 62 pregnant women with PIH (109 samples), mean age 29.1 years and (c) 75 healthy pregnant women (81 samples), mean age 28.5 years, used as matched controls. In pregnant women, blood collection started at the 10th week of gestation. In 14 women from group b and in 22 from group c blood was withdrawn during labor as well. CRH was assayed by RIA. Results: Levels in non-pregnant women were between 19.0-40.6 pg/ml (28.37 +/- 2.53 pg/ml, mean +/- S.E.M.). In both groups of pregnant women there was a progressive increase in plasma CRH levels becoming quite sharp towards the end of gestation. Between 10 and 20 weeks, CRH (mean +/- S.E.M.) in PIH group was 69.3 +/- 3.2 pg/ml versus 41.6 +/- 2.4 pg/ml in matched controls, at 21-25 weeks 168.0 +/- 12.8 pg/ml versus 58.5 +/- 3.8 pg/ml, at 32-35 weeks 1378.5 +/- 61.4 pg/ml versus 298.3 +/- 16.9 pg/ml and at 38 weeks 2800.0 +/- 114.1 pg/ml versus 825.0 +/- 59.8 pg/ml. At term, CRH levels were 3784.0 +/- 197.3 pg/ml in PIH, versus 1386.0 +/- 101.8 pg/ml in normal pregnancy. Statistically, at every stage of gestation, CRH levels were highly significantly different in the PIH group (P < 0.0005). One hour postpartum there was a c. 60% decrease in plasma CRH levels in both b and c groups. In three women with pre-eclampsia who underwent premature labor due to a dead fetus around the 30th week, very high levels were noticed in sequential blood samples for 4-5 weeks prior to labor. Conclusions: (a) CRH levels in women with PIH are significantly higher compared to healthy pregnant women at any stage of gestation starting from week 10; (b) very high levels during pregnancy might be predictive of premature labor or fetal loss; and (c) CRH measurement might prove to be a helpful diagnostic tool in women with pregnancy-induced hypertension