Oral, vaginal or intramuscular progesterone in programmed frozen embryo transfer cycles: a pilot randomized controlled trial

What should be the optimal route of luteal support in programmed frozen embryo transfer (FET) cycles?This was a randomized, parallel, phase IV pilot trial with three groups of women undergoing FET along with hormone replacement therapy for endometrial preparation at a tertiary private IVF centre (NCT03948022). Women with at least one autologous cryopreserved blastocyst were included. After preparing the endometrium with oestradiol, 151 women were randomly assigned to one of the following three progesterone arms before embryo transfer: oral (10 mg) dydrogesterone (DYD), total daily dose 40 mg (n = 52); 8% (90 mg) progesterone vaginal gel (VAG), total daily dose 180 mg (n = 55); or intramuscular progesterone (IMP) 50 mg/ml in oil, total daily dose 100 mg (n = 44). One or two vitrified-warmed blastocysts were transferred after 5 days' progesterone support.Baseline demographic features and embryological data were comparable among the groups. Ongoing pregnancy rates (40.4%, 38.2% and 45.5% in the DYD, VAG and IMP arms; P = 0.76) and live birth rates (40.4%, 38.2% and 43.2% in the DYD, VAG and IMP arms, P = 0.61) were statistically similar. Biochemical pregnancy rates and clinical miscarriage rates were also statistically similar among the groups. Significantly more patients with at least one side effect and moderate-to-severe side effects were documented in the IMP arm than the other groups (P < 0.001).Treatment with 40 mg/day oral DYD, 180 mg/day progesterone VAG gel or 100 mg/day IMP revealed similar reproductive outcomes in programmed FET cycles. Side effects were significantly more frequent in the IMP arm.