When did i conceive? i am 19 weeks pregnant as of january 20, 2012

Unless : Unless you had in-vitro fertilization, there is no exact answer to the question. However, if you are 19 weeks exactly on january 20th, your due date is probably june 14th. If you usually have 28 day cycles, and the cycle during which you became pregnant was a normal cycle for you, then your last period should have been september 8th, and you should have conceived on september 22. If you do not have exact 28 day cycles, then the rules change, and the answer depends on how regular your cycles are, if at all. The general rule (known as naegele’s rule) is to subtract 3 months from the first day of your last menstrual period, and then add 7 days. If your LMP was 9/8, then normally you would have a due date of 6/15, but only if you have 28 day cycles. I subtracted an extra day because there’s a leap year day next month! good luck with your pregnancy.