Usually, women ovulate one egg a month, a few may ovulate two eggs at a time, and there are cases where women ovulate twice a month, which cannot be generalized. If the patient usually has a normal regular menstrual cycle, she can ovulate once in about 28 days as the follicles gradually develop and mature by about 14 days during her period. Women have two ovaries, one on each side, and alternate ovulation irregularly on both sides to ensure that only one egg is ovulated each month. Occasionally, both sides ovulate, i.e., two eggs are ovulated in a month, and conception may occur in the same month with dizygotic twins. Normally, a menstrual cycle of 21 to 42 days is considered normal. If the menstrual cycle is short, it is possible to ovulate twice a month. In addition, ovulation is influenced by many factors, mainly hormone levels, and occasional non-ovulation or delayed ovulation can occur in normal people. In the presence of gynecological endocrine disorders, such as polycystic ovary syndrome, sporadic ovulation or non-ovulation may occur, affecting conception and requiring timely treatment.