Elevated blood flow resistance in uterine arteries of women with unexplained recurrent pregnancy loss

Background: Uterine perfusion appears to regulate uterine receptivity. However, vascular changes in recurrent pregnancy loss (RPL) remain poorly studied. Methods: One hundred and twentyone women were enrolled into this study: normal women with sterility caused by male factor (control group: n = 72) and women with RPL (n = 49). Women with uterine anomaly, impaired glucose tolerance, abnormal thyroid function, or anti-phospholipid antibodies were excluded from the study. In the mid-luteal phase of a non-pregnant cycle, transvaginal pulsed Doppler ultrasonography of the uterine artery was performed. Uterine arterial pulsatility index (PI), endometrial thickness, serum estradiol, progesterone, and nitrite/nitrate concentrations were determined. Results: In the RPL group, the PI in the uterine artery of women with antinuclear antibodies was significantly higher than that of women without antinuclear antibodies (P < 0.05). Among women without antinuclear antibodies, the mean (±SD) uterine artery PI in the RPL group (2.44 ± 0.41) was also significantly higher than in the control group (2.19 ± 0.40; P < 0.01). The PI was inversely correlated with serum progesterone levels (r = -0.47, P < 0.01). Conclusions: Elevated uterine arterial impedance is associated with RPL. Pulsed Doppler ultrasonography is useful in identifying women with unexplained RPL who have impaired uterine circulation.