If your baby due data is May 17 2009 when did you conceived?

To calculate the date of conception when you know the due date, subtract 266 days from the due date. In this case, the calculation would be:

May 17, 2009 - 266 days = August 10, 2008

Therefore, the estimated date of conception would be August 10, 2008. Please note that this is an estimate and the actual date of conception may vary depending on the individual.