Effects of Maternal Age on Euploidy Rates In a Large Cohort of Embryos Analyzed with 24-chromosome Single-nucleotide Polymorphism-based Preimplantation Genetic Screening

Objective: To determine the effect of maternal age on the average number of euploid embryos retrieved during oocyte harvest as part of an in vitro fertilization (IVF) cycle, including the probability of retrieving at least one euploid embryo in a cohort (PrE).

Design: Retrospective study.

Setting: Preimplantation genetic screening (PGS) laboratory.

Patient(s): Women aged 18 to 48 years undergoing IVF treatment.

Intervention(s): Use of 24-chromosome single-nucleotide polymorphism (SNP)-based PGS of day-3 and day-5 embryo biopsies.

Main Outcome Measure(s): Relationships between maternal age and the rate of embryos that tested as euploid (hereafter referred to as "euploid embryos"), the average number and proportion of euploid embryos per IVF cycle, and PrE.

Result(s): We analyzed 22,599 day-3 embryos and 15,112 day-5 embryos. In women aged 27 to 35 years, the median proportion of euploid embryos in each cycle remained constant at ∼35% in day-3 biopsies and ∼55% in day-5 biopsies, but it decreased rapidly after age 35. On average, women in their late 20s had four euploid embryos (day 3 or day 5) per cycle, but this number decreased linearly (R(2) ≥ 0.983) after 35 years of age. The effect of maternal age on PrE was similar, with a rapid exponential decline (R(2) = 0.986). Across all maternal ages, the euploid proportion and number of embryos per cycle were counterbalanced, so the number of euploid embryos per cycle was the same for day-3 and day-5 biopsies. This suggests that the loss of embryos from day 3 to day 5 was primarily due to aneuploidy.

Conclusion(s): Our results confirm the known inverse relationship between advanced maternal age (>35 years) and embryo euploidy, demonstrating that equal numbers of euploid embryos are available at day 3 and day 5.