Live birth following transfer of a euploid blastocyst derived from a 5PN zygote: a case report

Abnormal pronuclear formation, including five pronuclei (5PN), is generally considered indicative of abnormal fertilization (e.g., polyspermy or failure of polar body extrusion) and leads to routine embryo discard in many IVF programs. However, emerging evidence suggests that a minority of embryos with atypical pronuclear patterns may develop into a blastocyst and present diploid constitution after genetic testing, challenging the assumption that abnormal pronuclear morphology invariably predicts non-viability.

We report a rare case in which a 5PN zygote developed into a morphologically high-quality blastocyst was confirmed euploid-diploid by PGT-A, transferred in a subsequent frozen embryo transfer cycle, and resulted in the live birth of a healthy child.

This case adds to the limited but growing evidence that embryos with atypical pronuclear presentation may retain reproductive potential when development on time-lapse appears coherent and validated genetic testing confirms diploidy and euploidy, supported by appropriate patient counseling and informed consent.