My wife didn't really want to. She wasn't hellbent against it, just didn't really want it.
I would point to her aunts and ask her, now imagine your aunts if none of your cousins had ever been born? Another day I'd say, look at your grandmothers and imagine their lives if they'd never had any children.
I'd just drop things like that, never really pressing the issue, letting her chew on it. One day she woke up and started crying that she wanted a fat baby with lots of rolls. I did what I had to and we're due in August.