If you were told you conceived on February 10 2007 and the first day of your lmp was January 27 2007 but when you do the pregnancy calculators they say you are 5 weeks pregnant--how is that possible?
Pregnancy supposedly (medically) lasts for 40 weeks. In reality it lasts for 38 weeks from conception. Conception occurs approximately 14 days after your last period started for a woman who has a 28 day cycle. So everyone's pregnancy is based on these mythical 14 days eventhough very few women have a 28 day cycle! Medically they count these 14 days within the 40 weeks you are pregnant. You are considered 2 weeks pregnant at the moment of conception! Therefore three weeks after "The Deed" you are considered 5 weeks pregnant. Your doctor will not really care when you fell pregnant, s/he will be more concerned about the date of your last period and count from there.