Abstract
In the process of in vitro fertilization (IVF), zygote is considered as normally fertilized when there are two pronuclei (PN), one from sperm and the other from oocyte, and with two polar bodies (PBs). However, it is not uncommon to encounter tripronuclear (3PN) zygotes when conducting PN check for IVF or intracytoplasmic sperm injection (ICSI). Embryos derived from 3PN zygotes often lead to implantation failure, miscarriages and molar pregnancies, and these embryos are routinely discarded or not allowed to be transplanted. Here we report a case where most of the patient's oocytes (14/20) were immature (MI, GV), or with large or giant PB. After fertilization with ICSI, almost all resulting zygotes (7/8) were 3PN. By removing one female PN in 6 3PN zygotes, two microsurgically enucleated zygotes developed into high-quality blastocysts. One euploid blastocyst was selected for transfer after non-invasive chromosome screening (NICS), vitrification and thawing. The transfer resulted in the live birth of a healthy boy who is now 9-month-old and has no any health or developmental impairments.