I'm getting married, but I don't want children...?

What can I tell relatives and nosy aquaintances when they ask, "How many children do you want?" and I say, "None, he's getting fixed as a wedding gift!" to lighten the mood again? I mean, I'm pretty sure that him getting a vasectomy for me is the sweetest thing he could do, but these people are breeders who think that everyone who can should have children, help!