If you want to know how many days after sex can you take a pregnancy test, here is the answer-not immediately. You should not be so much excited about getting pregnant as to test for pregnancy immediately after having unprotected sex. You will be disappointed as it will turn negative and you will start wondering if you did the exam well or if you had the right brand of pregnancy test and so forth. To be practical you have to have unprotected sex when you are fertile and after this you have two weeks in which to test for pregnancy. This is because after two weeks you may or may not have your period, which may or may not prove pregnancy. This is not to say that you cannot test for pregnancy after the two weeks, but what will be the logic for testing if you have your period (assuming you have them?) it is best to test for pregnancy within these two weeks, but not in the first week as it is too early and will not be conclusive. If you have had sex after ovulation and you are sure of that, give yourself a period of seven days before testing for pregnancy as the chances of this being positive will be high.