A woman can be detected at the latest about 20 days after sex, usually by taking a blood test for increased levels of chorionic gonadotropin, which can be highly suspected of early pregnancy, in most cases after a woman has sex during ovulation. If the egg and sperm are able to unite and develop into a fertilized egg for transplantation into the uterine cavity, the level of human chorionic gonadotropin secreted by the corpus luteum of the ovary will increase 6-7 days after sexual intercourse, and a blood test can assist in the diagnosis of early pregnancy. If the fertilized egg is slow to develop or transplanted into the uterine cavity, it will reach the uterine cavity around 20 days after sex and can be detected. Therefore, women should also pay attention to keep their mood relaxed after sex to facilitate endocrine balance, which can also help detect changes in hormone levels earlier.