Multinucleation of a sibling blastomere on day 2 suggests unsuitability for embryo transfer in IVF-preimplantation genetic screening cycles.

Objective: To evaluate the impact of multinucleation of a sibling blastomere of day 2 embryos on the rate of aneuploidy detected by day 3 preimplantation genetic screening (PGS) biopsy and the effect on subsequent implantation and pregnancy rates.

Design: Retrospective cohort study.

Setting: University-based IVF center.