When did you get pregnant if your due date is on December 13?

That would probably put your last period around March 8th.. your fertile period was most likely March 20-25th.. it's pretty hard to tie it down to a certain date unless you only had sex a couple times the month you got pregnant. ~pawsalmighty You most likely conceived on or around March 23. Visit the site below which will give you an accurate reading on all conception dates, menstrual dates and due dates. http://www.genetree.com/about/conception-calculator.asp