Subcutaneous progesterone provide similar ongoing pregnancy rate compared to intramuscular progesterone in hormone replacement therapy frozen embryo transfer cycles

Open AccessPublished:November 10, 2022DOI:
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      To compare the ongoing pregnancy rates (OPRs) for subcutaneous progesterone (SC-P) to intramuscular progesterone (IM-P) in hormone replacement therapy used frozen embryo transfer (FET) cycles.


      Prospective non-randomized cohort study


      Private fertility clinic


      The study enrolled 224 patients scheduled for HRT-FET cycles with SC-P (n=133) or IM-P (n=91). The route of P administration was decided according to the patient’s preference and accessibility to the hospital. The first FET cycle of a freeze-all cycle using single blastocyst transfers, female age ≤35 was included.

      Main Outcome

      Ongoing pregnancy (OP)


      The demographic, cycle, and embryologic characteristics were similar between groups. The clinical pregnancy rates [86/133(64.7%) vs 57/91(62.6%); p=0.757], miscarriage rates [21/86(24.4%) vs 10/57(17.5%); p=0.329], and OPR [65/133(48.9%) vs 47/91(51.6%); p=0.683] were comparable between the SC-P and IM-P groups. Binary logistic regression for ongoing pregnancy as the dependent factor revealed that blastocyst morphology was found to be a significant independent prognosticator (for poor quality embryos Adjusted OR: 0.11, 95% CI for Adjusted OR: [0.029-0.427], p <0.001) and progesterone route (SC-P vs IM-P) was an insignificant prognosticator (Adjusted OR: 0.694 95% CI for Adjusted OR: [0.354-1.358], p: 0.694).


      The OPR for SC-P administration was similar to that for IM-P in HRT-FET cycles. The effect of ET day P levels may vary regarding the administration route. Randomized controlled trials comparing different progesterone administration routes are needed and large scale prospective trials are warranted to evaluate the ET day P levels on pregnancy outcome.

      Key Words