The number of days after intercourse to have an early pregnancy reaction varies from person to person. Some people may experience early pregnancy reactions such as nausea and vomiting and loss of appetite about 15 days after intercourse, while others may not feel any discomfort throughout the pregnancy. Therefore, it is more accurate to take a pregnancy test about 15 days after intercourse or to check human chorionic gonadotropin at the hospital about 10 days after intercourse to determine if you are pregnant. Normally, it takes some time for the sperm and egg to unite after intercourse, and the fertilized egg will come to bed about 8 days after intercourse, and the early pregnancy reaction will occur only when the HCG concentration in the blood rises to a certain level 6-7 days after successful implantation. The presence or absence of early pregnancy reaction depends on the sensitivity of the pregnant woman to human chorionic gonadotropin, so the earliest number of days to have a reaction is individual and cannot be generalized. In addition, it should be noted that women who are preparing for pregnancy must pay attention to stop smoking and drinking, take folic acid supplements and other substances, and avoid taking medication as much as possible.