Go to a search engine and type in "pregnancy calculator". Several sites will pop up saying they have one. What's great about this is if you have a cycle that isn't 28 days, you can get a more accurate due date. Now, I conceived approximately November 15th on a 28 day cycle and my due date is August 22nd if that helps. However you have to keep in mind that doctors consider the first day of your last period as the conception time. That leaves room for up to 2 weeks error on the due date. If your due date is 20 September than you most likely conceived on or around 29 December. I have provided you with a site below that gives you an accurate reading on conception dates, due dates based on menstrual dates. http://www.genetree.com/about/conception-calculator.asp
may 16th
June first week.
The approximate date of conception was February 27th 2009
The approximate date of conception was June 27th
September 20 2008
May
Usually ob/gyn's calculate the due date from the first day of her last period. Somewhere between the 16 or the 20 of February. Depend on when she ovulated, length of monthly cycle and the first day of her last period.
April
February 13th 2010 (give or take a few days)
Pregnancies usually last around 9 months, so it would be January 31st, or around then. It could be around January 15th if you conceived when most think it did happen. However, new research says that a pregnancy can last 15-20 days less than the due date or 15-20 days more. It then makes it very difficult to pinpoint the exact date.
September 20, 2013
September 20/21, 2008