Clinical Report: Evaluation of Serum Progesterone Levels as a 'Rescue' Intervention

Overview

This study evaluates the outcomes of hormone replacement frozen embryo transfer (HRT-FET) cycles with low pre-transfer progesterone levels and the impact of a single-dose rescue intervention. Findings indicate that pre-ET progesterone levels below 5 ng/mL are associated with lower live birth rates and higher miscarriage rates.

Background

Hormone replacement frozen embryo transfer (HRT-FET) cycles rely on exogenous progesterone for successful implantation. Low serum progesterone levels have been linked to reduced pregnancy outcomes.

Data Highlights

Key Findings

• Pre-ET P4 levels <5 ng/mL were associated with a live birth rate of 19.2%.
• Miscarriage rates were 46.7% for pregnancies with pre-ET P4 <5 ng/mL compared to 9.9% for levels ≥5 ng/mL.
• The live birth rate for the rescue group with P4 ≥5 ng/mL was similar to the no-rescue group (41.8% vs. 39.2%).
• Among borderline cycles (P4 9.1–9.9 ng/mL), the live birth rate was numerically higher with rescue (57.1%) than without (40.0%).
• ROC analysis indicated a Youden cutoff of 5.3 ng/mL for pre-ET P4 levels.

Clinical Implications

Clinicians should consider the implications of low pre-transfer progesterone levels when planning HRT-FET cycles. Shared decision-making is advised for patients with P4 <5 ng/mL, as this group may have significantly poorer outcomes.

Conclusion

The findings suggest that low pre-ET progesterone levels are associated with poor reproductive outcomes, highlighting the need for careful management in HRT-FET cycles.

Related Resources & Content

1. Frontiers in Endocrinology, 2026 -- Association between serum progesterone levels on the day of embryo transfer and clinical pregnancy outcomes in POSEIDON Group 1 patients
2. Frontiers in Endocrinology, 2026 -- Outcomes of frozen embryo transfers from a large monocentric cohort (2982 cycles): towards a preferential use of cycles with a corpus luteum for endometrial preparation
3. The Journal of Clinical Endocrinology & Metabolism -- Effects of Negative Pregnancy Experiences in the First IVF Cycle on Future Pregnancy Results
4. The Journal of Clinical Endocrinology & Metabolism -- Evaluation of Cumulative Live Birth Rates in Preimplantation Genetic Testing Cycles: Progestin Versus GnRH Analogues
5. Preparation of the endometrium for frozen embryo transfer: an update on clinical practices - PMC
6. Impact of low serum progesterone levels on the day of embryo transfer on pregnancy outcome: a prospective cohort study in artificial cycles with vaginal progesterone - PubMed
7. Effectiveness of progesterone rescue in women presenting low circulating progesterone levels around the day of embryo transfer: a systematic review and meta-analysis - PubMed
8. Preparation of the endometrium for frozen embryo transfer: an update on clinical practices - PMC
9. Impact of low serum progesterone levels on the day of embryo transfer on pregnancy outcome: a prospective cohort study in artificial cycles with vaginal progesterone - PubMed
10. Effectiveness of progesterone rescue in women presenting low circulating progesterone levels around the day of embryo transfer: a systematic review and meta-analysis - PubMed