Impaired Uterine Artery Blood Flow at Mid Gestation and Low Levels of Maternal Plasma Corticotropin-Releasing Factor

Abstract

Objective: Corticotropin-releasing factor (CFR) 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.

Methods: 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 unilaterla 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.

Results: 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 unilaterla (168.45 ± 27.5 pg/mL; P < .01) or bilaterla (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).

Conclusion: 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.