Effect of ovulation induction on uterine blood flow and oestradiol and progesterone concentrations in early pregnancy.

To determine if oestradiol and progesterone concentrations are related to uterine blood flow in early pregnancy, we measured these hormones at the time of vaginal Doppler ultrasound before and after the beginning of intervillous circulation in spontaneous pregnancy (group I), after clomiphene citrate administration (group II), and after clomiphene citrate plus human menopausal gonadotrophin (HMG) administration (group III). Despite large increases of oestradiol concentration in group II (60%) and III (300%) and of progesterone in groups II (100%) and III (300%), compared with group I, increases in blood flow were modest during the first 9 weeks of gestation. Uterine artery flow volume increased by 20% in group II and 33% in group III (P < or = 0.02); average velocity increased by 37% in group III (P < or = 0.003) compared with groups I and II; vessel diameter increased by 15% in groups II (P < 0.025) and III (P < 0.001) compared with group I; and the uterine artery resistance index decreased by 3 to 5% in group III (P = 0.004) compared with groups I and II. Serum oestradiol and progesterone concentrations were unrelated to the uterine artery resistance index or volume by an analysis of covariance. We conclude that uterine artery blood flow is significantly increased during early pregnancy following HMG administration, and that the increase is unrelated to increases in oestradiol and progesterone concentrations.