Oral micronized progesterone versus vaginal progesterone for luteal phase support in fresh embryo transfer cycles: a multicenter, randomized, non-inferiority trial.

This article reports on a multicenter, randomized, non-inferiority trial conducted in China comparing oral micronized progesterone to vaginal progesterone gel for luteal phase support (LPS) in fresh embryo transfer cycles following in vitro fertilization (IVF). The study found that oral micronized progesterone at 400 mg per day resulted in a non-inferior ongoing pregnancy rate compared to vaginal progesterone gel at 90 mg per day, while a higher oral dose of 600 mg per day was associated with a lower ongoing pregnancy rate and an increased risk of preterm delivery. No significant differences were observed in live birth rates or most maternal and neonatal complications among the groups, although oral administration was linked to a higher incidence of vaginal bleeding/spotting. These findings suggest that oral micronized progesterone 400 mg/day may be a viable alternative to vaginal progesterone gel for LPS in fresh embryo transfer cycles triggered by human chorionic gonadotropin (hCG), but further research is needed to confirm optimal dosing and safety.