Birth of Thirty-Two Healthy Babies Following Transfer of Fresh and Frozen-Thawed Embryos Derived from Monopronuclear Zygotes: A Retrospective Study.

Fertilized zygotes normally display two pronuclei (PN), but abnormal fertilization patterns (0, 1 or >2PN) are observed daily in IVF labs. Multiple PN zygotes (>2) are generally discarded due to an increased risk of aneuploidy. However, the decision to transfer or not transfer 1PN-derived embryos remains controversial.