Egg-breaking injection refers to a hormone that is injected when the follicle has developed and matured in order to calculate the optimal time for conception; it is human chorionic gonadotropin (HCG). Because HCG acts similarly to the function of luteinizing hormone (LH), the application of HCG injections when the follicle has reached imminent maturity predicts ovulation within 1-2 days of the injection, which is helpful in guiding natural coitus fertilization, artificial insemination, or egg retrieval procedures. Before the egg-breaking injection, the follicle growth should be monitored by ultrasound examination. Usually the follicle develops to about 1.8-1.9cm is the most appropriate time, and the effect of the injection should be affected if it is given early or late. Most women will ovulate within 36 hours after the egg-breaking shot, and a few ovulate within 24 hours. Women who need egg retrieval in the fertility department usually have their eggs retrieved 36 hours after the injection, for example, if the injection is given at 8:00 pm on the 1st, 8-10:00 am on the 3rd is the best time for egg retrieval. In addition to accurately predicting the time of ovulation, the purpose of the ovulation injection is to enable the granulosa cells in the follicle to be converted into corpus luteum cells, so that the corpus luteum can function better, and to help the oocyte to eventually transform into a mature oocyte, and to improve the situation that some women’s follicles are not easy to be ruptured when they are ripe.