The exact ovulation period varies from woman to woman due to different menstrual cycles and menstrual patterns. In women with regular menstrual cycles, ovulation occurs about 15 days before the next menstrual period, or around the 15th day of menstruation. For women with irregular menstrual cycles, ovulation cannot be predicted by the date, as abnormal menstrual cycles can lead to endocrine abnormalities and ovulation can be affected. If you do not have a normal menstrual cycle, you can measure ovulation by ovulation test paper, and you can measure ovulation according to your basal body temperature and ultrasound to clarify the specific ovulation period. If a strong positive ovulation test is performed and found, ovulation will be successfully completed within 48 hours. During the ovulation period, the temperature will rise from the lowest point by about 0.5°C. When the follicle diameter is about 18mm during the ultrasound monitoring, it means that the follicle is mature and may be expelled at any time.