Does frozen embryo transfer improve pregnancy outcomes in patients with ovarian endometriosis? A retrospective cohort study.

RESEARCH QUESTION: Does frozen embryo transfer improve pregnancy outcomes compared with fresh embryo transfer in women with ovarian endometriosis (OEM) undergoing their first IVF/intracytoplasmic sperm injection cycle?

DESIGN

A retrospective cohort study analysed 550 women aged 20-40 years with ultrasound-confirmed OEM who underwent their first assisted reproduction cycle between January 2020 and December 2023. Participants underwent either fresh embryo transfer (n = 170) or frozen embryo transfer (n = 380). Baseline characteristics including ovarian reserve markers, stimulation protocols, and embryo features were compared. Clinical outcomes assessed were clinical pregnancy, live birth, implantation, pregnancy loss, preterm birth, and neonatal complications. Multivariate regression models adjusted for potential confounders. Subgroup analyses considered progesterone concentration, oocyte yield, status of adenomyosis, prior surgery or medical therapy for OEM, endometrial preparation protocols, and stages of transferred embryos.

RESULTS

Women in the frozen embryo transfer group had a shorter duration of infertility and higher levels of ovarian reserve markers. Unadjusted analysis showed higher implantation, clinical pregnancy and live birth rates in the frozen embryo transfer group; however, after adjustment, no significant differences were observed in implantation rate [adjusted relative risk (RR) 0.89, 95% CI 0.67-1.19], clinical pregnancy rate (adjusted RR 0.90, 95% CI 0.68-1.19), live birth rate (adjusted RR 0.94, 95% CI 0.67-1.32), and other pregnancy and neonatal outcomes. Subgroup analyses confirmed these findings.

CONCLUSIONS

Frozen embryo transfer does not confer a benefit over fresh embryo transfer for improving the live birth rate or reducing pregnancy complications in women with OEM. Fresh embryo transfer remains a viable and potentially more time- and cost-efficient option in this patient population.