Protocol for Ovarian stimulation
Controlled ovarian stimulation was performed using the routine long GnRH
agonist protocol. Oocytes were retrieved transvaginally 34–36 h after
human chorionic gonadotropin (hCG) administration, and fertilization was
assessed 16–18 h after routine insemination or ICSI. Blastomere number
and regularity, as well as the presence and volume of cytoplasmic
fragmentation, were assessed 24 and 48 h later, respectively. According
to the protocol developed by Chinese legislation, no more than two
embryos were transferred on day 3 or 5 after oocyte retrieval. The
remaining available embryos were cultured for blastocyst formation.
Then, all patients received luteal support after embryo transfer,
including intramuscular injections of progesterone in oil or vaginally
administered micronized progesterone.