Oral dydrogesterone vs. micronized vaginal progesterone gel for luteal phase support in frozen-thawed single blastocyst transfer in good prognosis patients.

Objective: To investigate the efficacy of oral dydrogesterone for luteal phase support (LPS) in modified natural cycle frozen-thawed embryo transfers (mNC-FET) compared to micronized vaginal progesterone (MVP) gel.

Methods: This was a randomized, single-center, parallel controlled trial conducted at an ART and Reproductive Genetics Centre within a private hospital between January and August 2019. A total of 134 women, aged below 38, were assigned randomly to receive oral dydrogesterone (n=67) or MVP (n=67) for LPS in mNC-FET. The primary outcome was ongoing pregnancy rate (OPR) and secondary outcomes were clinical pregnancy and miscarriage rates, patients' satisfaction and tolerability of oral and vaginal progesterone. A questionnaire was developed to compare patient satisfaction and side effect profiles.

Results: There was no significant difference in demographic features such as female age, body mass index, AMH levels and fresh cycle characteristics between two groups (p>0.05). When mNC-FET outcomes were compared, OPR was 68.7 % in MVP gel group and 71.6 % in the dydrogesterone group respectively percentage difference, -2.99; 95 % CI: -17.96, 13.10) Biochemical and clinical pregnancy rates and biochemical and clinical miscarriage rates were also similar between two groups. A significantly higher patient tolerability score was present in the dydrogesterone arm (4.09 ± 0.96 vs 3.36 ± 1.23, p=0.001).

Conclusion: Our results suggest that oral dydrogesterone provides similar ongoing pregnancy rates compared to MVP gel as a LPS in mNC FET. Since dydrogesterone is an effective and easy-to-use option with fewer intolerable side effects including vaginal irritation, vaginal discharge, and preventing sexual intercourse, it can be used as LPS in mNC FET.