“When did I conceive, this is one of the most common questions we are asked by pregnant women (unless it is obvious!). Well we decided to give you guidelines to answer that question.  Now that you’ve received the wonderful news, there are several key dates at the beginning of your pregnancy that can help you calculate your due date and your conception date, including the first day of your last menstrual period . Here’s a quick rundown on how the calculations are made.

Doctors count the length of a pregnancy as 280 days, which equals 40 weeks or 10 months. Why not nine months? The counting begins with the first day of your last normal menstrual period before you got pregnant. In other words, the counting begins about two weeks before you have even conceived.

It starts at that point primarily it is because it is difficult to pinpoint the exact date a woman conceived, and the first date of her last menstrual period is a much easier marker to identify. Once you have that date down, you can establish your estimated due date by adding 40 weeks, or 280 days.

You can chart your ovulation cycle and this can help you pinpoint your conception date more accurately, if that is important to you.