Most doctors and nurses that you will talk to throughout your pregnancy will want to know the date of your last menstrual period, or LMP.
What's so important about your LMP?
Well, most pregnant women aren't sure of the actual date of conception (when the egg was fertilized). Unless you are charting your cycle each month, it can be very difficult to pinpoint the specific date. But if you know the date of your LMP, that can give a ballpark range of when you likely conceived. Why? The typical menstrual cycle (from period to period) lasts about 28 days, and ovulation usually occurs around day 14. So if you know the date of your LMP, then the doctor can reasonably estimate the date you conceived, which then helps determine your due date.
You may have some questions about your LMP:
1. What if I have irregular cycles (shorter/longer than 28 days)?