A test paper can be used to determine when intercourse is fertile. When luteinizing hormone peaks, it means that a woman is in the 24-48 hours before ovulation and intercourse is most fertile when ovulation occurs. Conception requires the union of sperm and egg to form a fertilized egg, which is transported through the ureter into the uterine cavity and successfully implanted in the endometrium before conception is complete. The completion of conception should be considered from two aspects: 1) for men, they should have a regular life and a healthy diet; 2) for women, they should monitor the ovulation time, because basically only one egg is ovulated in each menstrual cycle, and the test paper monitoring method is usually used. Ovulation test strips are usually used to predict ovulation by detecting the peak level of luteinizing hormone, which usually appears in the urine within 24-48 hours before ovulation. In daily life, it is recommended not to smoke or drink for 3 months before pregnancy, not to contact with radioactive substances and not to use drugs indiscriminately, to strengthen nutrition, to develop good living habits and diet, and to eat more foods rich in vitamins.