Does maternal age at retrieval influence the implantation potential of euploid blastocysts?

Age-related decline in reproductive potential is mainly due to the increased incidence of aneuploidy. Furthermore, 2 recent studies have shown that euploid embryos of older women may have a lower implantation potential compared to those of younger women, suggesting that aging might compromise embryos beyond their ploidy status. However, the inherent limitations of these studies preclude solid conclusions.

The aim of this study was to determine whether maternal age at retrieval affects the implantation potential of euploid blastocysts.

This is a retrospective cohort study that was conducted at an academic medical center. Patients who underwent frozen-thawed euploid embryo transfers (FET) between 2013 and 2016 were included. Cycles were divided into the following 5 age groups: <35, 35-37, 38-40, 41-42, and >42 years of age. Blastocysts were assessed before biopsy and assigned the following morphological grades: excellent (3-6AA), good (3-6AB, 3-6BA), average (2-6BB), and poor (3-6BC, 3-6CB, 3-6CC). The main outcome measures were implantation (IR) and live birth (LBR) rates. Both χ² and Fisher exact tests were used to compare categorical variables. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated and controlled for confounders.

A total of 785 FET cycles (870 blastocysts) were included. Excellent-quality blastocysts were associated with a significantly higher LBR compared with good-quality (78.8% vs 63.8%), average-quality (78.8% vs 54.2%), and poor-quality (78.8% vs 28.3%) counterparts. Poor-quality embryos yielded a higher spontaneous abortion (SAB) rate compared with average-, good-, and excellent-quality blastocysts (25.0%, 9.0%, 6.9%, and 2.4%, respectively). Embryos biopsied on day 5 had a significantly higher LBR compared with those biopsied on day 6 (60.0% vs 46.6%). The 5 age groups (<35, 35-37, 38-40, 41-42, and >42 years) had comparable IRs (56.5%, 52.9%, 55.4%, 59.1%, and 71.4%, respectively), LBRs (55.1%, 51.3%, 53.5%, 52.4%, and 61.9%, respectively), and SAB rates (8.8%, 7.9%, 8.3%, 14.3, and 13.3%, respectively). Older women had fewer euploid embryos, but they were of comparable morphology and developed at a similar rate to the blastocyst stage as compared to those of younger women.

Maternal age at retrieval influences the number of euploid embryos; however, contrary to previously published studies, it does not affect their implantation potential. The morphodynamic characteristics of embryos, as reflected by blastocyst morphology and speed of development, are critical for selecting among euploid embryos.