They heard a scream as Jon saw what was happening to himself. He ran out of the restroom, to find them as Emily made the wish. But once she had made the wish, she heard another scream.
Karyn opened the door to see Jon there, falling down, as his belly got bigger and his pregnancy advanced by months in a few seconds. Yelling in pain again, Jon gave birth.
And now Jon was a mother, but of course Jon was no longer pregnant.