Ovulation stimulation injections used in antagonist protocols usually take about 10 days. By antagonist regimen people generally refer to the use of GnRH antagonists, which are safer and often used in patients with poor ovarian function who do not ovulate. Generally patients start using GnRH antagonists to promote ovulation on the 3rd day of menstruation after a detailed physical examination and use them until the follicle reaches about 20 mm in diameter. The exact number of days of drug use depends on the development of the follicle, and most patients need to use the drug for about 10 days to achieve the desired effect. During the treatment period, the growth and development of the follicles as well as the hormonal changes in the body should be regularly observed and the medication regimen should be adjusted in a timely manner.