Pregnancy can be detected at two weeks after intercourse. If you have sex during ovulation and do not use contraception, if the sperm and egg unite to form a fertilized egg, and if the egg is successfully laid, human chorionic gonadotropin will begin to be produced on the sixth day after ovulation. At the earliest, when blood is drawn 7 days after intercourse, the HCGH in the blood is significantly elevated, and then it doubles every other day, and can reach about 100u/L when blood is drawn at two weeks after intercourse. The blood test can be used to detect pregnancy earlier than the urine test, and can be used to monitor the development of the embryo by taking a blood test for elevated values of human chorionic gonadotropin in the blood. If it is more than 2 weeks since intercourse, the test can be performed in urine or blood, respectively, to determine if you are pregnant, with guaranteed accuracy.