Do serum progesterone levels on embryo transfer day predict live birth in true natural cycle frozen embryo transfer cycles?
ESHRE 42nd Annual Meeting of ESHRE, ESHRE 2026, London, İngiltere, 5 - 08 Temmuz 2026, cilt.1, sa.1, ss.158-159, (Özet Bildiri)
- Yayın Türü: Bildiri / Özet Bildiri
- Cilt numarası: 1
- Doi Numarası: 10.1093/deag083.226
- Basıldığı Şehir: London
- Basıldığı Ülke: İngiltere
- Sayfa Sayıları: ss.158-159
- Acıbadem Mehmet Ali Aydınlar Üniversitesi Adresli: Evet
Özet
Study question: Do serum progesterone levels on the day of embryo transfer predict live birth rates in true natural cycle frozen embryo transfer (tNC-FET) cycles? Summary answer: In tNC-FET cycles, serum progesterone levels on the day of embryo transfer were not associated live birth when analyzed across different progesterone percentiles. What is known already: Adequate progesterone exposure is essential for endometrial transition to the secretory phase, successful implantation, and maintenance of early pregnancy. In artificially prepared FET cycles, low serum progesterone levels -particularly below 10 ng/ml- have been associated with diminished live birth rates. In one retrospective, serum progesterone levels on the day of embryo transfer were not found to affect ongoing pregnancy rates, whereas another retrospective study reported lower live birth rates when progesterone levels were below 10 ng/ml. However, in tNC-FET cycles, no consensus threshold has been established, and existing evidence remains inconsistent. Study design, size, duration: This prospective cohort study included tNC-FET cycles performed at a single tertiary IVF centre between 2022 and 2025. All eligible cycles with documented serum progesterone measurement on the day of embryo transfer and complete treatment outcome data were included. Outcome was defined as live birth (delivery of at least one live-born infant beyond 24 weeks of gestation) or no live birth (not pregnant, biochemical pregnancy, miscarriage, delivery before 24 weeks of gestation). Participants/materials, setting, methods: Patients undergoing tNC-FET with confirmed ovulatory cycles were included. Ovulation was defined by a serum progesterone level exceeding 1.0 ng/mL accompanied by a simultaneous decline in estradiol levels. No luteal phase support was administered prior to embryo transfer. Serum progesterone levels on embryo transfer day were categorized into distribution-based quartiles: Q1 (4-<9.88 ng/mL), Q2 (9.88-<12.45 ng/mL), Q3 (12.4-<16 ng/mL), and Q4 (16 ng/mL). Univariable analyses, multivariable logistic regression, and positive predictive value analyses were performed. Main results and the role of chance: Of the 430 included cycles, 236 (54.9%) resulted in live birth. No significant differences were observed between cycles with and without live birth in terms of maternal age, body mass index, endometrial thickness, infertility duration, embryo quality or serum progesterone levels on the day of embryo transfer. The proportion of double embryo transfer was significantly higher in cycles resulting in live birth. Live birth rates, embryo quality and number of embryos transferred did not differ across distribution-based progesterone quartile groups. In multivariable logistic regression analysis adjusted for maternal age, BMI, infertility duration, endometrial thickness, number of embryos transferred, and embryo quality, serum progesterone quartiles were not independently associated with live birth compared with the reference group (12.4-<16 ng/mL). The adjusted odds ratios were 1.20 (95% CI 0.72–2.01) for 4-<9.88 ng/mL, 1.05 (95% CI 0.64–1.71) for 9.88-<12.45 ng/mL, and 0.793 (95% CI 0.54– 1.59) for >16 ng/mL. Double embryo transfer remained independently associated with live birth (adjusted OR 1.82, 95% CI 1.16– 2.87). Live birth probabilities remained stable across progesterone quartiles in predictive probability analyses. Limitations, reasons for caution: The single-center design may limit generalizability of the findings. Although the study was prospectively conducted, its observational nature does not allow for causal inference. Wider implications of the findings: These findings suggest that, in tNC-FET protocols, serum progesterone levels on the day of embryo transfer do not predict live birth. Routine progesterone monitoring for the purpose of defining threshold values in tNCFET cycles may therefore be of limited clinical value. Trial registration number: No