Q: How long does it take for a women to get pregnant after having sex? My LMp is 3rd March but I made relation with my husband between 15th to 18th March (that was high fertility window) . I did my pregnancy test on 13th April and it was positive. But now the confusion is how many weeks pregnant I am? If I check according to my LMP then I am 9 weeks pregnant and if I check according to conception then it's 7 weeks. Can anyone explain this to me? Thanks. I hope you understood my question.