It remains under subject of debate regarding the optimal route of luteal support for hormone replacement therapy- frozen embryo transfer (HRT-FET) cycles. We compared efficacy of vaginal progesterone gel combined with oral dydrogesterone and intramuscular progesterone for HRT-FET lutein support.

This is a retrospective observational study. After matching for propensity score of getting vaginal + oral treatment, a total of 208 FET cycles in the vaginal progesterone combined with oral dydrogesterone and 624 cycles in the intramuscular progesterone group were enrolled. Pregnancy outcomes and neonatal outcomes including chemical pregnancy rate, clinical pregnancy rate, implantation rate, spontaneous abortion rate, live birth rate, gestational weeks, pre-term delivery, birth weight, and congenital anomalies rate were compared.

No significant differences were observed in patient characteristics such as age, duration of infertility, type of infertility, or hormone level after matching. Chemical pregnancy rate (68.3 % versus 70.5 %), clinical pregnancy rate (64.9 % versus 64.4 %), implantation rate (52.3 % versus 50.2 %), spontaneous abortion rate (21.5 % versus 18.4 %), and live birth rate (49.0 % versus 51.3 %) were similar in both group without statistically significant difference. No significant differences in neonatal outcomes were observed between the two groups.

We observed similar pregnancy outcomes in both vaginal progesterone gel combined with oral dydrogesterone and intramuscular progesterone protocol. Vaginal progesterone gel combined with oral dydrogesterone can be substituted for intramuscular progesterone given that vaginal plus oral use has good safety and is more convenient and may be associated with less side effect caused by intramuscular injection.