If you have intercourse on the day of ovulation, if fertilization occurs on the 5th-6th day after ovulation, the chorionic gonadotropin in the blood will be elevated on the 7th day, which means that you are pregnant. If there is no elevation of chorionic gonadotropin after seven days, it means that you are not pregnant, because blood tests are the most accurate. Therefore, if you want to have a baby, you can have intercourse three days before and two days after the day of ovulation, plus the day of ovulation on alternate days, so there is usually no delay in pregnancy. However, if the fallopian tubes are blocked or the endometrium is not normal, there may also be no pregnancy.