This is a randomized, double-blind, single center clinical trial study to compare the oocyte maturity, embryo development, and risk of ovarian hyperstimulation syndrome (OHSS) after receiving the standard dose of human chorionic gonadotropin (hCG) ovulation trigger or a lower dose of hCG plus concomitant follicle stimulating hormone (FSH) co-trigger in women undergoing in vitro fertilization (IVF).