Misoprostol’s effect on uterine arterial blood flow and fetal heart rate in early pregnancy

Abstract

Objective: To determine whether a single oral dose of misoprostol is associated with change in Doppler resistance indices (RIs) of the uterine artery in early pregnancy. Methods: Forty pregnant women seeking legal termination of pregnancy at 7–15 completed gestational weeks were each given a single oral dose of 200 μg misoprostol. Resistance indices (A/B ratio) and pulsatility index (PI) of the uterine arteries (UA) and fetal heart rate (FHR) were assessed by Doppler ultrasound before and 1 hour after administration of misoprostol. Results: Doppler RIs (UA-A/B and UA-PI) of the right and left uterine arteries increased significantly 1 hour after misoprostol administration. The right UA–A/B increased from 7.16 ± 1.09 (mean ± SEM) to 10.26 ± 0.67 ( P < .001), and the left UA–A/B increased from 7.40 ± 0.72 to 9.21 ± 0.82 ( P = .04). The right UA–PI increased from 2.38 ± 0.11 to 2.90 ± 0.12 ( P < .001), and the left UA–PI increased from 2.38 ± 0.17 to 2.70 ± 0.18 ( P = .03). No significant changes in FHR were noted 1 hour after misoprostol administration. None of the fetuses died during that time. Conclusion: Doppler RIs of the uterine arteries increased significantly after single oral doses of misoprostol during the first trimester, implying a reduction in arterial blood flow. Those changes were not associated with fetal death, possibly explaining congenital abnormalities associated with misoprostol in early pregnancy.