babies assuming they are not born too early or late have a gestation of 280 days so you will need to do some backward counting. remember that a due date is just a guesstimate based on the last normal menstrual period so these dates can be notoriously wrong too. finding the exact day of conception is usually very difficult if not impossible unless the pregnant woman knows some specific facts that could better pinpoint the magic moment.
my daughter is expecting a baby with a due date of november 26 2014. what would the conception date be?