Uteroplacental circulation in early pregnancy complicated by threatened abortion supplemented with vaginal micronized progesterone or oral dydrogesterone

Objective: To compare the influence of vaginal micronized progesterone and oral dydrogesterone supplementation on uteroplacental circulation in early pregnancy that is complicated by threatened abortion. Design: Randomized parallel group, double-blind, double dummy-controlled study. Setting: Tertiary care university hospital. Patient(s): Fifty-three patients with threatened abortion and a living embryo. Intervention(s): Three hundred milligrams of micronized vaginal progesterone or 30 mg of oral dydrogesterone daily supplementation for 6 weeks, serial transvaginal Doppler ultrasound measurement of pulsatility index, resistence index, and systolic/diastolic ratio of the spiral arteries, the uterine arteries, and the intrachorionic area. Main Outcome Measure(s): Uteroplacental blood flow. Result(s): The study demonstrated that vaginal progesterone administration, but not oral dydrogesterone treatment, results in the decrease in the spiral artery pulsatility and resistance index and systolic/diastolic ratio. Insignificant decrease in pulsatility index and resistance index of the uterine artery was observed at > 9 weeks and was not associated with treatment regimen. Dydrogesterone treatment was only accompanied by the decrease in the uterine artery systolic/diastolic ratio. Conclusion(s): Vaginal progesterone and oral dydrogesterone supplementation have a different influence on the uteroplacental circulation in early pregnancy that is complicated by threatened abortion.