Ovulation occurs about 14 days before menstruation. Some changes will occur in the body during ovulation, such as an increase in leucorrhea, in the form of straining, sometimes accompanied by some mild abdominal pain, or bleeding during ovulation. Intercourse during ovulation is very easy to conceive. If you do not intend to prepare for pregnancy, you must take reasonable contraceptive measures to avoid unwanted pregnancy, which is not good for your health. The 3-5 days before and after menstruation are the safe period, when no eggs are expelled and the conditions for conception are not met, even if no contraceptive measures are taken. The method of calculating the safety period and ovulation period is only suitable for women with regular menstruation, such as irregular menstruation, often early or late, and can not accurately calculate the ovulation and safety period. At this time, you can use ovulation test paper to detect ovulation, when the test paper appears weak positive or strong positive, it means that ovulation will come, when the test paper appears negative represents the safe period, but the accuracy of the test paper is not 100%.