She wants his child, more than anything else, although it means she will surely die giving birth, and she wants him to love their child.
He wants her to live, more than anything else, so he hates the unborn child, because it is already taking her life away.
Love and hate, birth and death. Edward and Bella leave each other no choice. This is perhaps the only time in Breaking Dawn when they drift very far apart from each other, and love between them seems to die for a short while...