The pregnancy cannot be detected during ovulation. A mature egg is discharged during ovulation, and if you have sex at this time, it is possible for the sperm to combine with the egg to form a fertilized egg and become pregnant. But even if you are pregnant, the HCG in your body has not risen to a certain level, so no matter whether you take a blood test for HCG or use pregnancy test paper to check your urine, due to the time is too short, can not be detected, at least you need to have sex about 10 days after taking a blood test for HCG may be detected. If you take a urine test with pregnancy test paper, it needs to be about 15 days after sex. If the test is positive, the pregnancy is confirmed. If the test is negative, you need to take another test a week later to confirm the pregnancy.