Impaired uterine artery blood flow at mid gestation and low levels of maternal plasma corticotropin-releasing factor.

Abstract

Corticotropin-releasing factor (CRF) is a placental neuropeptide that plays a role in the control of uteroplacental blood flow regulation. Because CRF has a relaxant effect on uterine vasculature in pregnant rats, we aimed to evaluate mid-gestation plasma CRF levels in women with impaired uterine artery blood flow. Maternal plasma CRF was assayed by specific radioimmunoassay, and uterine artery resistance index (RI) was assessed by Doppler evaluation at 22-24 weeks' gestation in 55 healthy pregnant women, of whom 24 showed a unilateral or bilateral uterine artery notch, reflecting resistance. Statistical analysis was performed by the Kruskal-Wallis test followed by the post hoc Dunn's test and the Spearman rank test. The mean uterine artery RI was significantly (P <.001) higher in women with a notch than in healthy controls. Mean +/- standard error of the mean maternal plasma CRF levels were significantly lower in women with a unilateral (168.45 +/- 27.5 pg/mL; P <.01) or bilateral (186.07 +/- 34.5 pg/mL; P <.001) uterine artery notch than in healthy control pregnant women (375.06 +/- 21.77 pg/mL). Although no difference was found in CRF levels between patients with a unilateral or bilateral uterine artery notch, a significant inverse correlation was found between the mean RI and maternal plasma CRF levels (Spearman r = -0.6540; 95% confidence interval, -0.7865, -0.4640; P <.001). Reduced levels of circulating CRF were associated with increased uterine artery resistance, which supports the hypothesis that CRF may regulate uterine artery tone at mid gestation.