Multicenter Assessment of Outcomes After Intended or Non-selective Transfer of Whole Chromosome and Segmental Aneuploid Embryos.

Objective

To evaluate the clinical outcome potential of embryos classified by preimplantation genetic testing for aneuploidy (PGT-A) as non-mosaic whole chromosome aneuploid (WCA) or segmental aneuploid (SA) in a large multicenter consortium study.

Design

Multicenter retrospective cohort study. SUBJECTS Data were obtained from eight of the 26 fertility centers participating in the International Registry of Mosaic Embryo Transfers (IRMET) network that contributed non-mosaic WCA and SA embryo transfers between 2016 and 2026. The study included 250 embryo transfers (168 WCA and 82 SA) with complete clinical outcome documentation. Transfers were performed either with knowledge of the PGT-A result at the time of transfer or as non-selective transfers performed without knowledge of the PGT-A result. EXPOSURE Trophectoderm biopsy at blastocyst stage followed by PGT-A using whole-genome amplification (WGA) and next-generation sequencing (NGS). MAIN OUTCOME MEASURES Pregnancy and neonatal outcomes.

Results

Among 168 WCA transfers, including 111 performed without knowledge of the PGT-A result at the time of transfer, no live births occurred. Most transfers resulted in no pregnancy (78.6%), with smaller proportions showing biochemical pregnancy (8.3%), ectopic pregnancy (1.8%), early spontaneous abortion (9.5%), late spontaneous abortion (1.2%), or therapeutic termination (0.6%). In contrast, SA transfers (n = 82) resulted in a 17.1% live birth rate. Neonatal data available for 10 SA live births showed no differences in gestational age or birthweight compared with live births following euploid embryo transfer at the same centers, and prenatal or neonatal genetic testing were normal in all tested cases.

Conclusions

In this large multicenter dataset of non-mosaic whole chromosome and segmental aneuploid embryo transfers, embryos classified as uniformly whole chromosome aneuploid produced no live births, whereas segmental aneuploid embryos retained a modest yet clinically meaningful potential for live birth. These findings support the biological validity of PGT-A classification of whole chromosome aneuploid embryos and highlight the distinct clinical implications of whole chromosome and segmental aneuploidies.