For women with a regular menstrual cycle of 28 days, the ovulation day is mostly around 14 days before the next menstrual period. 3 days before and 3 days after the ovulation day, plus the ovulation day, a total of 10 days, is called the ovulation period. During the follicular phase, estrogen secretion increases with the gradual development of follicles, and estrogen reaches a peak near ovulation, which lasts for 48 hours and can act positively on the hypothalamus and pituitary gland to produce follicle-stimulating hormone and luteinizing hormone, leading to ovulation of mature follicles. After ovulation, the corpus luteum forms and secretes estrogen and progesterone. Generally, estrogen and progesterone reach another peak on the 7th and 8th day after ovulation, and the negative feedback acts on the pituitary gland to reduce the secretion of luteinizing hormone and follicle stimulating hormone, and the endometrium sheds, i.e., menstruation. In addition, ovulation in women can be influenced by many factors, such as emotions, diet, living habits, environment, etc. The specific ovulation date can be monitored by ovulation test paper or ultrasound.