Microstimulation is an ovulation promotion protocol that involves in vitro fertilization and embryo transfer after ovulation promotion with small doses of gonadotropins, clomiphene or letrozole, without descending regulation. It is increasingly accepted for its advantages of being “safe, efficient and less intrusive”. Microstimulation is mainly used in the following cases: 1. Patients of advanced age with declining ovarian reserve: For patients of advanced age with poor ovarian reserve and with low quantity and poor quality of eggs obtained by conventional ovulation: microstimulation is less expensive and can be used for several consecutive egg retrievals, resulting in fewer mature eggs but higher quality eggs. This allows time for multiple egg retrievals in order to save enough high-quality embryos for frozen embryo transfer (screening of embryos prior to transfer using fluorescence in situ hybridization has shown that the rate of normal embryos obtained with the microstimulation protocol is higher than with the conventional protocol). A more satisfactory success rate can be achieved. 2. Poor ovarian response to conventional regimen: Clinical practice has confirmed that for poor ovarian response, even increasing the dose of stimulating drugs does not significantly increase the number of follicles, improve egg quality and increase the pregnancy rate, while facing the side effects of high dose stimulating drugs and expensive costs. Microstimulation protocols reduce the dose of ovulatory drugs, shorten the treatment time, and increase the number of cycles to obtain better quality embryos to achieve the desired pregnancy rate. 3. For a small number of patients with polycystic ovary syndrome who have experienced ovarian hyperstimulation with previous stimulation: microstimulation protocol is more economical and safe by minimizing the effective dose of stimulation and using GnRH-a as the trigger drug (conventional trigger drug is HCG), which significantly reduces the patient’s discomfort and risk of ovarian hyperstimulation. Microstimulation used in patients with polycystic ovary syndrome also often results in about 20 eggs, but without the presence of thoracoabdominal fluid, and the patient has no stomach pain, bloating, or shortness of breath. This advantage is also favored by many patients with severe oligospermia, teratospermia, and obstructive azoospermia, who can safely obtain multiple eggs to combine with these sperm of poorer quality and select the best quality embryos from multiple embryos for transfer. The use of microstimulation protocols can reduce drug stimulation and achieve results similar to those obtained with conventional ovulation protocols. However, since the microstimulation protocol does not have descending regulation, it is prone to early onset of LH peak and early ovulation, therefore, the following things should be noted when performing microstimulation protocol for ovulation: 1. Patients using microstimulation protocol should have their sex hormone levels checked 2-5 days after entering the cycle, and the doctor should adjust the medication for the patient according to the number of follicles measured by ultrasound, follicle diameter size, etc. and combined with blood values. 2. When the maximum follicle diameter measured by ultrasound reaches 14mm or the blood estrogen reaches a certain level, the patient needs to have blood tests every morning to monitor the appearance of LH peak. 3. The male partner needs to be near the hospital when the female follicle reaches 16mm and must not go out to facilitate coming to the hospital for sperm retrieval in case of emergency egg retrieval. For the male partner who cannot come to the hospital in time, he can freeze the semen in advance for emergency egg retrieval. 4. In patients who use clomiphene for ovulation in the microstimulation protocol, a thinner endometrium in the cycle is a normal drug reaction. 5. It is recommended to freeze the whole embryo in this cycle and arrange the frozen embryo transfer after the menarche or after 2-3 cycles of ovulation treatment with microstimulation protocol to obtain a certain number of embryos, which has a higher success rate. How to choose the best treatment plan to obtain high quality eggs and embryos and avoid complications requires the clinician to develop the most optimal and economical personalized treatment plan for the patient based on the patient’s specific situation, which requires active cooperation and communication between the patient and the doctor.