The absence of ovulation due to immaturity or post-maturity or pregnancy or oral contraceptive pills or dysfunction of the ovary. Comparison of Pregnancy Results of Natural Ovulation Cycle and Superovulation Cycle of Intrauterine Artificial Insemination by Donor 由于卵子不成熟、卵子成熟期已过、怀孕、服用避孕药或者卵巢功能紊乱等原因导致卵子无法排出。自然排卵周期与促排卵周期宫腔内供精人工授精的妊娠情况比较