Ongoing pregnancy rates in single euploid frozen embryo transfer remain unaffected by the female age at embryo creation and transfer: a retrospective study of 1923 single euploid frozen embryo transfer cycles

Research question Is female age a significant factor in the likelihood of an ongoing pregnancy in single euploid frozen embryo transfers (seFET)? Design Retrospective study of 1923 seFET cycles from 1464 women, either in a natural cycle (NC) or a hormonal replacement therapy cycle. 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 to ≤37, >37 to ≤40, and >40 years-old at OPU without a significant trend for decreasing OPRs (P=0.679). No significant differences between the groups (OPR vs. no pregnancy or miscarriage) were seen for female age at transfer (P=0.609) or at OPU (P=0.816). Women who received good quality embryos (P<0.001), with lower BMI (P<0.001), at least one previous pregnancy (P<0.001) and a NC (P<0.001) had significantly higher OPR. Multivariable regression (adjusted for BMI, embryo quality, endometrial preparation) analysis did not show a significant effect of female age at OPU on achieving an OPR. Compared to women ≤35-year-old, none of the age groups had significantly higher or lower pregnancy rates. A multinomial regression analysis showed that both, miscarriage and no pregnancy vs. ongoing pregnancy was associated with BMI, embryo quality and endometrial preparation. Again, female age had no significant associations with either outcome. Conclusion(s) The herein presented data demonstrate no substantial impact of female age on its own on the OPR in seFET cycles, but a significant impact of embryo quality, BMI, previous parity and a NC protocol.