It is well known that having intercourse during ovulation can increase the chances of conception. But how can we deduce when ovulation is? Actually, our body changes at different times of menstruation. These changes can be used as a reference for whether the ovaries are ovulating or not. 1. Time extrapolation: Our normal menstrual cycle is 28 days ± 7 days. Ovulation occurs about 14 days backward from the first day of menstruation (12-16 days). Those with a cycle less than 21 days or more than 35 days usually do not ovulate. Luo Ran, Fertility Center of Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine 2. Vaginal discharge inferred: The secretion of cervical mucus will gradually increase before ovulation, and it will be excreted as part of the leucorrhoea. At this time, the cervical secretion is thin in texture, clarified, like egg white, and can be stretched, and the vulva is moist. However, when there is inflammation in the vagina, cervix and uterus, the nature of the secretion can change and the ovulation characteristics are not obvious. Pelvic pain: Usually after ovulation, the oocyte and its appendages penetrate the follicular wall, the egg is picked up by the umbrella of the fallopian tube, and the outflow of follicular fluid stimulates the pelvic floor causing lower abdominal cramping or even pain. The pain threshold is different for each person, some feel it obviously, some feel it slightly, and some feel it. 4. Vaginal bleeding: Due to the sudden decrease of estrogen level in the body during ovulation, it sometimes causes endometrial breakthrough bleeding, which usually lasts for 2-3 days and the amount is not much. 5, combined with the current network of many ovulation testing tools, can provide some reference for inexperienced patients. The above points, for patients with regular menstrual cycle, can be used to understand some preliminary changes in the body during ovulation, which can increase the chance of conception if intercourse occurs at this time. However, this can only be used as a reference for ovulation, not as a basis.