Do unborn babies count for the US Census?

The questionnaire asks how many people were living at the house or apartment as of April 1. That would mean people already born. If you were pregnant, due around April 1, and mailed your form on March 25 and counted the unborn, I doubt that anybody would quibble over it. Someone down the street may have counted himself, mailed the form and died before April 1. That's not going to throw the count off enough to hurt anything. The overall number will be close enough.