how soon after having sex without a condom can i take a test to see if im pregnant. Most home pregnancy tests (the kind you can buy in drugstores) can detect pregnancy after a missed period, though some can detect it a few days before a missed period. Pregnancy actually doesn’t start the day a couple has intercourse. It can take up to six days after sex for the sperm and egg to join and form a fertilized egg. It then takes another six days for the fertilized egg to implant itself into the lining of the uterus to start a pregnancy.