The risk of embryo-endometrium asynchrony increases with maternal age after ovarian stimulation and IVF.

This retrospective cohort analysis examined the effects of maternal age on the incidence of factors associated with embryo-endometrium asynchrony in fresh autologous blastocyst transfer. The study included 1169 routine fresh autologous blastocyst transfers. The main outcome measure was asynchronous transfer defined by delayed (day 6) blastocyst transfer or elevated pre-ovulatory serum progesterone level. Compared with patients younger than 35 years, patients 35 years or older had increased risk of having at least one risk factor for asynchronous transfer, including premature progesterone elevation or delayed blastocyst transfer (RR 1.36; 95% CI 1.24 to 1.50). The older group had increased risk of simultaneously having both risk factors (RR 1.61, 95% CI 1.17 to 2.21) compared with the younger group. In patients younger than 35 years, live birth rate per transfer was 62.9% with day 5 transfer and low progesterone, declining to 27.9% for day 6 transfer combined with elevated progesterone. In patients 35 years or older, live birth rate per transfer was 38.0% with day 5 transfer and low progesterone, declining to 18.1% for day 6 transfer combined with elevated progesterone. Indicators of embryo-endometrium asynchrony increase in prevalence as women age and asynchrony disproportionately decreases birth rates in older patients.