Controlled ovarian stimulation is a technique that uses ovulation-promoting drugs and adjuvant medications to control folliculogenesis and development with the goal of obtaining the desired number and quality of eggs, and is irreplaceable for assisted reproductive technology in the treatment of infertility. IVF controlled ovulation protocols generally include four dosing regimens: long protocol, short protocol, microstimulation and natural cycle. The following is a brief description of these four regimens: Long regimen: gonadotropin-releasing hormone agonist (GnRHa) is started on day 21 of the previous menstrual cycle (known as mid-luteal phase) and has four main effects: suppressing early LH peaks, avoiding early ovulation in ovulation-promoting cycles, synchronizing the development of multiple eggs, and improving the endometrial tolerance to embryos. The use of ovulation-promoting drugs is started on day 14-16 after GnRHa administration, i.e. day 3 of the current menstrual cycle, followed by occasional ultrasound monitoring of follicle growth and blood sampling to determine estrogen levels, and judging the ovarian response to the drugs based on ultrasound and estrogen results and adjusting the dosage of ovulation-promoting drugs accordingly; until the doctor says the follicles are mature, 5000 -10000 IU of HCG is injected on the same day (usually at night) to promote ovulation. -After 36 hours of HCG injection (8:00 am on the next day of HCG injection), egg retrieval will be performed. The long protocol is suitable for patients with good ovarian function due to its higher and more stable success rate. Short regimen: GnRHa is started on day 2 of menstruation, when the positive regulating effect of GnRHa is utilized, i.e. the early stage of GnRHa use (around 1-3 days) is to promote the secretion of FSH and LH in the body, thus enhancing the ovulation promotion effect; the later stage of GnRHa use (when the follicles are gradually growing and maturing) gradually changes to the descending regulating effect; the ovulation promotion is started on day 3 of menstruation The dose of ovulation-promoting drugs will be adjusted according to the ultrasound and estrogen results; the eggs will be injected with 5000-10000 IU of HCG on the same day (usually at night) to promote egg maturation; 36 hours after HCG injection (the third day of HCG injection 36 hours after HCG injection (8:00 am on the third day of HCG injection), egg retrieval is performed. The short regimen is suitable for older patients or those with poor ovarian response. If these patients use the long regimen, they may have fewer follicles to produce or fewer follicles to grow due to the suppression of their own follicle stimulating hormone secretion by the downregulation effect, so the short regimen is more suitable for older patients or those with poor ovarian response. Microstimulation protocol: This is an ovulation promotion protocol that does not involve descending or ascending regulation of the pituitary gland. The stimulatory effect on the ovaries is relatively weak, mainly in comparison to the conventional treatment protocol in IVF, where the patient uses only a small amount of medication, and by reducing exogenous interference with follicle development, the few eggs obtained may be “selected” because they have undergone “natural selection” during the follicle development process. By reducing the amount of medication used, the few eggs obtained may be “naturally selected” due to their follicular development, and the doctor hopes to obtain eggs of better quality than those collected by conventional “ovulation promotion”. Microstimulation is currently not the first choice for all patients because the success rate is not as stable as conventional protocols, and can be a useful complement to conventional ovulation protocols. Natural cycle protocol: This means that ovulation is induced by stimulating the ovaries without any medication, i.e. one egg matures each month in the woman’s natural state and is then removed from the body by manual techniques. There are four advantages: access to naturally mature eggs; a natural hormone-induced endometrial environment that is more conducive to embryo implantation; no ovarian hyperstimulation and multiple pregnancies; and savings on medication costs. The disadvantages are as follows: the exact time of ovulation must be estimated by repeatedly monitoring the LH peak near the ovulation period, which is tedious and poorly operable in clinical work, and often no eggs can be retrieved; only one egg can be obtained, and if the egg retrieval fails, no eggs can be obtained; problems may occur in other parts of the culture operation, resulting in no embryos available for transfer. Natural cycles are suitable for patients with abnormal ovulation cycles, suspected of decreased egg quality due to ovulation; patients who are unresponsive or insensitive to ovulation-promoting drugs, failure to obtain more eggs with ovulation, etc. The use of natural cycles for egg retrieval is not currently advocated in patients with normal ovarian function. In conclusion, there are various ovulation promotion protocols and the doctor needs to consider the patient’s ovarian function and medical history review to develop the appropriate ovulation promotion protocol and implement individualized treatment to protect the patient’s best interests.