This is something that has a whole lot of ramifications, not the least of which is…
Is the real target “be(ing) pregnant” or having a baby (the typical result of pregnancy 😉 )?
What is the end desire on your part? Children? Her being pregnant? Or simply more sex?
What part of “pregnancy” is she resisting? The pregnancy itself, the sex to get there, or the child that results?
If you’re seeing a pattern, that’s because these all need to be addressed. If you push just “pregnancy”, maybe she will decide she wants to be a Surrogate, and get in-vitro fertilized with some other couple’s child, who will then be given away at the end. (VERY unlikely outcome, but if she hates sex and doesn’t want kids of her own, well…)