2024-12-2920241472-648310.1016/j.rbmo.2024.1040742-s2.0-85195609063https://doi.org/10.1016/j.rbmo.2024.104074https://hdl.handle.net/20.500.14288/23055Research question: Is female age a signi fi cant factor in the likelihood of an ongoing pregnancy in single euploid frozen embryo transfers (FET)? Design: Retrospective study of 1923 single euploid FET cycles in 1464 women, either in a natural cycle or a hormone replacement therapy cycle. The primary outcome was the ongoing pregnancy rate (OPR). Results: There were 990 (51.48%) ongoing pregnancies among 1923 included transfers. The OPR were 51.4%, 49.1%, 53.3% and 52.3% for women aged < 35, > 35 -< 37, > 37 -< 40 and > 40 years at oocyte retrieval (OCR), without a signi fi cant trend for decreasing OPR ( P = 0.679). No signi fi cant differences in female age at embryo transfer ( P = 0.609) and female age at OCR ( P = 0.816) were found between the groups (ongoing pregnancy versus no pregnancy or miscarriage). Women who received good-quality embryos ( P < 0.001), had a lower body mass index (BMI) ( P < 0.001), had achieved at least one pregnancy previously ( P < 0.001), and underwent natural cycle endometrial preparation ( P < 0.001) were more likely to achieve an ongoing pregnancy. Multivariable regression analysis (adjusted for BMI, embryo quality and endometrial preparation) did not show a signi fi cant effect of female age at OCR on achieving an ongoing pregnancy. Compared with women aged < 35 years, none of the age groups had signi fi cantly higher or lower OPR. A multinomial regression analysis showed that BMI, embryo quality and endometrial preparation were associated with miscarriage/no pregnancy versus ongoing pregnancy ( P = 0.001, 0.001 and 0.001, respectively). Female age had no signi fi cant association with either outcome. Conclusions: Female age in itself does not have a substantial impact on the OPR in single euploid FET cycles, but the OPR is impacted signi fi cantly by embryo quality, BMI, previous parity, and a natural cycle endometrial preparation protocol.Obstetrics and gynecologyReproductive biologyJournal article1472-64911253022600001Q141194