When to go for IVF depends on the different ovulation protocols the doctor has developed for the patient. For example, patients with the short-acting long luteal phase protocol need to come to the hospital 7 days after ovulation to enter the cycle for ovulation, while the long follicular phase protocol, short protocol and antagonist protocol usually come to the hospital on the 2nd-3rd day of menstruation for ovulation, and then perform HCG injection trigger after the follicle development reaches the standard, retrieve the eggs about 36 hours after the injection, and fertilize the eggs with sperm In vitro fertilization is performed and cultured into day 3 oogenesis embryos or day 5 blastocysts, while fresh embryos are transferred and the remaining embryos are frozen and preserved. If the fresh embryos are not pregnant after the transfer, you can come to the hospital directly for frozen embryo transfer without further egg retrieval. For patients who use the natural cycle endometrial preparation protocol for frozen embryo transfer, embryo thawing transfer is usually performed 3-5 days after ovulation, while for patients who use the artificial cycle for endometrial preparation, embryo transfer is performed 3-5 days after the addition of progesterone.