When I was pregnant with our first child (three years ago) I dropped a lot of subtle - and even more not-so-subtle hints about an eternity ring. Husband was a bit resistant to the idea but eventually he came around.
However, because I'd put on such a vast amount of weight when pregnant, I didn't want it straight away as I wanted the right ring for my hand when slimmer.
I still have an IOU for it, but the way I see it, the longer I leave it, the bigger the budget
Not sure what I should get for having our second child though. He's 6 months old now, and there's been no mention of matching earrings or anything like that .....