Ovulation monitoring is a common indicator to assess ovarian function in women. The main methods of ovulation monitoring are: measurement of basal body temperature, assessment of cervical mucus, ultrasound monitoring, and hormone measurements, including hormone measurements in urine and blood. The most commonly used method is the combination of urinary LH measurement and vaginal ultrasound monitoring and simultaneous monitoring of follicular growth and development to observe whether ovulation is occurring. In general, a normal woman who is ovulating usually develops one dominant follicle and expels one mature oocyte per month. For patients who require outpatient ovulation promotion followed by guided conception or IUI, we generally use a microstimulation ovulation protocol with the goal of obtaining 1-2 well-developed mature follicles and synchronized development of the endometrium. The Royal Society of Fertility states that if ≥4 dominant eggs develop during the cycle (mean follicle diameter ≥14mm), strict contraception is required to avoid ovarian hyperstimulation and multiple births, and IUIs are eliminated. General protocol for follicle monitoring For women with a menstrual cycle of 28-30 days, the development of the dominant follicle starts on day 6-8 of the menstrual cycle. You can decide the next monitoring time after the initial monitoring on day 11-12 of the menstrual cycle according to the size of the dominant follicle, usually 3-4 times per cycle for ultrasound monitoring, at the following times: 1. The largest follicle diameter <10mm< The next monitoring interval is 6-7 days when the largest follicle is <10mm; 2. 3-4 days when the dominant follicle is 10-12mm in diameter; 3. 2-3 days when the dominant follicle is 13-15mm in diameter; 4. 1-2 days when the dominant follicle is 16mm or more in diameter; 5. The disappearance or collapse of follicles monitored by ultrasound indicates that ovulation has occurred. In the ovulation promotion cycle, when the follicle diameter is >18-20mm, it indicates that the follicle has matured and can be injected with HCG and observed for ovulation after 48 hours. Individualized protocol for follicle monitoring 1. In patients with irregular menstrual cycles, the time of initial monitoring should be appropriately adjusted according to the length of the menstrual cycle, with appropriate postponement in those with longer menstrual cycles and appropriate advancement in those with shorter menstrual cycles. 2. Adjust the time interval of this monitoring accordingly according to the speed of previous follicle development; for patients with early ovulation of the dominant follicle in the past, the frequency of monitoring will be increased when the follicle has developed to 14mm or more. When the dominant ovulation has developed and matured to 18-23mm in diameter, the natural cycle can be followed by a self-test of basal body temperature, which rises >0.5°C (approximately 36.7°C or more) followed by a repeat ultrasound to observe whether ovulation has occurred. 3. If no dominant follicle is observed by about day 20-25 of the cycle, it can be considered as anovulatory cycle and further treatment should be clarified by consulting the doctor. In patients with anovulatory cycles, to ensure ovulation, better timing of conception and to enhance luteal function, ovulation is routinely induced with human chorionic gonadotropin (HCG) injection to guide the couple to conceive. 48 hours after HCG injection, if the mature follicles have disappeared or collapsed, progesterone can be given appropriately for luteal support for 14 days, and after 14 days, menstruation will not come and combined with urinary HCG Further judgment. To determine if there is pregnancy, if HCG is positive, continue luteal support until vaginal ultrasound monitoring is performed about 5 weeks after ovulation. If no pregnancy occurs in this cycle, the drug can be stopped until the onset of menstruation and a new cycle of ovulation treatment will need to be started from day 1-4 of the next menstrual cycle.