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

Objective: To determine whether a single oral dose of misoprostol is associ ated with change in Doppler resistance indices (RIs) of the uterine artery in early pregnancy. Methods: Forty pregnant women seeking legal termination of pregnancy at 7-1 5 completed gestational weeks were each given a single oral dose of 200 lug misoprostol. Resistance indices (A/B ratio) and pulsatility index (PI) of the uterine arteries (UA) and fetal heart rate (FHR) were assessed by Doppl er ultrasound before and 1 hour after administration of misoprostol. Results: Doppler RIs (UA-A/B and UA-PI) of the right and left uterine arter ies increased significantly I hour after misoprostol administration. The ri ght UA-A/B increased from 7.36 +/- 1.03 (mean st 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 misoprosto l administration. None of the fetuses died during that time. Conclusion: Doppler RIs of the uterine arteries increased significantly aft er single oral doses of misoprostol during the first trimester, implying a reduction in arterial blood Row. Those changes were not associated with fet al death, possibly explaining congenital abnormalities associated with miso prostol in early pregnancy. (C) 2000 by The American College of Obstetricia ns and Gynecologists.