What are the jewish mourning custom regarding a baby who was born dead?
Actually there are no jewish mourning custom regarding a baby who was born dead, because that according to the jewish ‘HALACHA’ (law) a baby under 30 days is considered ‘NEFEL’ (could not find an exact translation so, something like ‘unborn’ or ‘nonexistent’) and because he was never considered “alive” there no customs when he dies. I agree that isn’t the best Jewish call of all times, and hope the question is for someone else, but that’s the thing with ‘HALACHA’ – it is what it is.