If the female follicle is a high quality follicle, the estrogen level is relatively matched, the thickness of the endometrium is relatively matched, and the male partner’s sperm does not suggest clear oligo-weak malformed spermatozoa, no increase in DNA fragmentation, and no incomplete transmission of genetic material, intercourse two days before ovulation is completely possible to get pregnant. If the patient has no oligo-weak deformed spermatozoa and the sperm quality is good, pregnancy is possible two days before ovulation; 2. The quality of the female ovarian follicles, such as whether the follicle size is greater than 18mm, the estrogen value whether it is greater than 200 pg/ml, whether the thickness of the endometrium is greater than 8mm, whether the growth matches the ovaries, etc.; if the infertility time frame is more than one year for women, it is recommended to do a hysterosalpingogram to assess whether the fallopian tubes are patent, if male factors are excluded.