[Association between maternal age and chromosomal status of pre-implantation embryos].

Objective: To analyze the chromosome status of pre-implantation embryos from women of different ages, and assess the impact of age on it.

Methods: A retrospective analysis was carried out on the results of PGT-A and PGT-M+PGT-A cycles by whole-genome amplification followed by next generation sequencing at the Second People's Hospital of Nanning between July 2021 and November 2023. The embryos were divided into five groups based on the women's age: ≤ 30 years old group, 31 ~ 34 years old group, 35 ~ 37 years old group, 38 ~ 40 years old group, and ≥ 41 years old group.The chromosomal status of embryos for each group was compared. This study has been approved by the Ethic Committee of the Hospital (Ethics No. Y2024312A).

Results: This study has involved 390 couples and 436 PGT cycles, with a total of 1 651 blastocysts biopsied and analyzed. Among these, 835 embryos (50.6%) were found to have chromosomal abnormalities, including 490 (29.7%) with aneuploidies, 154 (9.3%) with chromosomal segment abnormalities, and 264 (16.0%) with chromosome mosaicisms. After adjusting the dosages of Gn, female BMI, male age, PGT indications, infertility type, LH, AMH and other parameters, maternal age appeared to be an independent factor for chromosomal abnormalities and aneuploidies in blastocysts (OR = 1.132, 95%CI = 1.089-1.177, P < 0.001; OR = 1.250, 95%CI = 1.188-1.315, P < 0.001). With the increase in female age, embryonic chromosome abnormalities have significantly increased in each group, with the rates being 32.3% (126/390), 43.1% (189/439), 45.1% (116/257), 66.3% (250/377), and 81.9% (154/188) (P < 0.001). Chromosomal aneuploidies have also significantly increased, with the rates being 8.2% (32/390), 16.6% (73/439), 24.5% (63/257), 49.6% (187/377), and 71.8% (135/188) (P < 0.001). The proportion of embryos with ≥ 2 chromosome abnormalities also significantly increased in abnormal embryos, with the rates being 28.6% (36/126), 30.2% (57/189), 39.7% (46/116), 48.4% (121/250), and 64.9% (100/154) (P < 0.001). Of note, the female age did not affect the prevalence of chromosomal segment abnormalities and mosaicisms (all P > 0.05).

Conclusion: Above findings suggested that along with the increase in female age, there is an increase in the rate and complexity of chromosomal abnormalities, which may contribute to infertility in women with elder age.