If the intramuscular injection of urotropic gonadotropin is started on the 5th day of menstruation, the injection is given once/day at 75 units/time for 5 days, and then the follicles are monitored by ultrasound on the 12th-13th day of menstruation, and another ultrasound is done on the 14th-15th day of menstruation to see if the original follicles have grown. If the diameter of the follicle reaches about 18mm on the 15th day of menstruation, the dominant follicle can be injected intramuscularly with chorionic gonadotropin, and then the follicle will rupture and expel the egg. This is the whole process of ovulation promotion. In clinical practice, ovulation promotion does not necessarily take one month, but several months or even half a year to be successful.