Comparison of intramuscular versus subcutaneous aqueous progesterone for luteal phase support in artificially prepared frozen embryo transfer cycles

OBJECTIVE: Cryopreservation of embryos for future transfer attempts has noticeably increased in the last decade, especially due to the technological developments in in vitro fertlization (IVF) laboratories. In parallel, different progesterone (P) replacement regimens preceding artificially prepared frozen embryo transfer (AC-FET) attempts, especially with respect to the route of application and dosing scheme, have been widely argued so far. We aimed to provide more information about the efficacy profile of novel subcutaneous aqueous progesterone (SP) in AC-FET cycles. MATERIALS AND METHODS: This retrospective, single-centre cohort study included a total of 507 AC-FET cycles performed between June 2018 and April 2020. Three hundred forty-nine (68.8%) patients received 50 mg of intramuscular progesterone as once daily, 158 (31.2%) patients received 25 mg of SP as twice daily. Only, the first and single blastocyst transfers from the same cohort were accepted. The inclusion criteria were as follows: females aged <37 years, body mass index ≥18 kg/m(2) and ≤35 kg/m(2), sperm concentration ≥5x10(6)/mL. Pre-implantation genetic testing cycles were not included. The primary outcome was the live birth rate (LBR). RESULTS: The number of previous IVF attempts, type of infertility, peak estradiol (E2) levels, the total number of retrieved oocytes, mature oocytes, and the number of 2PN was significantly different between the groups. Positive pregnancy (p=0.474) and clinical pregnancy rates (p=0.979), LBR (p=0.404), and missed abortion rates (p=0.144) were comparable between the groups. The total number of oocytes [adjusted odds ratios (AOR)=1.024, 95% confidence interval (CI): 1.002-1.047; p=0.03)], endometrial thickness (AOR=1.121, 95% CI: 1.003-1.253; p=0.044), and cryopreservation day 5/6 (AOR=0.421, 95% CI: 0.226-0.788; p=0.007) achieved statistical significance following binary logistic regression analysis. However, P administration type did not achieve statistical significance (p=0.731). CONCLUSION: As a novel option, SP has comparable efficacy in pregnancy outcomes and may be accepted as an alternative for luteal phase support in AC-FET cycles.