P-285 Serum progesterone level may not impact ongoing pregnancy rate (OPR) in patients with endometriosis undergoing frozen-warmed-blastocyst transfer employing hormone replacement treatment (HRT) with subcutaneous progesterone
Authors: Ince O , Cimsit Kemahli M  N , Yarali Ozbek I , Mumusoglu S , Yarali H 
Published: July 2024

Study question

Do serum progesterone (P4) levels on frozen embryo transfer (FET)-1 day impact OPRs in patients with endometriosis undergoing HRT-FET with subcutaneous progesterone (sc P)?

Summary answer

In HRT cycles employing sc P, serum P4 levels on FET-1 day do not affect OPRs in patients with or without endometriosis.

What is known already

In HRT-FET cycles employing vaginal P, reproductive outcomes are improved by serum P4 monitoring and employing a rescue protocol, if needed. However, there is paucity of data for the need of serum P4 monitoring in HRT cycles employing sc P. Endometriosis is associated with P4 resistance. There is only one study evaluating the impact of serum P4 levels on reproductive outcomes in patients with endometriosis; in this study lacking a control group and employing vaginal P gel 90 mg/12 hours supplemented by daily 50 mg intramuscular P, a threshold of 37.1 ng/ml has been reported for improved live birth rates.

Study design, size, duration

Retrospective cohort study. 451 consecutive patients undergoing their first HRT- vitrified warmed blastocyst transfer during November 2021-June 2023 at Anatolia IVF Centre were included. 44 patients had endometriosis with surgical and/or ultrasound findings and the remaining 407 patients did not harbor endometriosis. The presence of adenomyosis was an exclusion criterion. Following 10-12 days of 6 mg/day estradiol valereate use, sc P 25 mg/12hours (Prolutex, Ibsa) was administered. The primary outcome measure was OPR.

Participants/materials, setting, methods

Serum P4 levels were measured 4-5 hours after morning administration of sc P on FET-1 day. The impact of serum P4 on OPRs was assessed at various percentiles adjusting for female age, body mass index, prior birth, preimplantation genetic testing for aneuploidy, number/grade of blastocysts transferred. Multivariate regression models were performed in the whole cohort incorporating polynomial P4 terms and endometriosis interactions; optimal model for OPR prediction was selected using the lowest Akaike Information Criteria.

Main results and the role of chance

Patients with (27/44, 61.4%) and without (214/407, 52.6%) endometriosis had comparable OPRs. In the endometriosis group, the 10th, 50th, and 90th percentiles of serum P4 were 15.6, 25.1, and 35.4 ng/ml, respectively, compared to 14.9, 23.5, and 35.6 ng/ml in the non-endometriosis group. In the endometriosis group, the OPRs were 60.0%, 66.7%, 56.3%, and 60.0% for the &lt;10p, 10-50p, 50-90p, &gt;90p groups, respectively. These figures were 46.3%, 50.3%, 56.8%, and 51.2%, in the non-endometriosis group, respectively. In the endometriosis group, taking the 50-90p group as the reference, the adjusted odds ratios (aORs) for OPR of &lt; 10p, 10-50p, and &gt;90p groups were 1.24 [0.03, 50.45], 1.77 [0.31, 10.24], and 2.08 [0.05, 80.23], respectively. In the non-endometriosis group, the respective aORs were 0.85 [0.40, 1.79], 0.80 [0.49, 1.29], and 0.72 [0.34, 1.50]. In the multivariate regression analysis to determine the optimal model, neither serum P4 levels (aOR for linear term: 1.11 [0.98, 1.26]; for quadratic term: 0.998 [0.996, 1.00]) nor the diagnosis of endometriosis (OR: 1.48 [0.74, 2.98]) significantly predicted ongoing pregnancy after adjusting for confounders. Additionally, the optimal model did not include the interaction term, suggesting that endometriosis does not significantly modify the impact of serum P4 levels on OPRs.

Limitations, reasons for caution

The study’s limitations include retrospective study design, a limited sample size of the endometriosis cohort, absence of laparoscopy for endometriosis exclusion in the non-endometriosis group, and lack of data on endometriosis phenotypes.

Wider implications of the findings

In HRT-FET cycles employing sc P 25 mg/12hours neither serum P4 nor the presence of endometriosis have an impact on OPRs. Endometriosis may not modify the impact of serum P4 on OPRs suggesting a lack of P resistance in such cycles or the overcoming of P resistance by this regimen.

Trial registration number

not applicable