Live birth following vitrification of in vitro matured oocytes derived from sibling smaller follicles at follicle selection phase in the context of in vitro fertilization.

In ovarian stimulation, a 31-year-old woman with polycystic ovary syndrome was at the risk of developing ovarian hyperstimulation syndrome, follicle aspiration was performed, and eight immature oocytes were collected from follicle fluids. After 28 h in vitro culture, six of them reached MII and were vitrified. The patient failed to conceive in her fresh in vitro fertilization cycle and next two replacement cycles. In the third replacement cycle, a successful pregnancy was obtained by vitrified-thawed oocytes. This case demonstrates that follicular aspiration during follicle selection phase has protective effects against developing ovarian hyperstimulation syndrome, and rescued immature oocytes are viable and could produce promising embryos for live birth.