There's a real balancing act between mother & baby. Human pelvic bones are jointed & move to create more room to give birth. Babies skulls also have joints, so the skull can be compressed to allow delivery.
While the question about hip width is important, it's not the only factor to be considered. Are pelvic joints different, the same? Are skull joints the same or different? Bone density?
I’ve amused myself with that one, that so-called interbreeding would more likely produce lower infant mortality if the mom was Neandertal...