When did you conceive if your baby is due April 19 2011?

You conceived on July 11, 2010. because Due date is an approximate date calulated by adding 280 days from last period. [On average, your pregnancy should last around 40 weeks, or 280 days, from your last period]
so substract 280 days from April 19 2011 gives July 11 2011.
Dr Rahul Parikh