There was a piece in The Times yesterday suggesting the idea of "negative child benefit" - effectively taxing those who can't/won't/don't have kids:
"Introduce a “negative child benefit” tax for those who do not have offspring. This may seem unfair on those who can’t or won’t have children, but...
We do a 'big shop' fortnightly, we used to manage that for £100-ish for a household of two, topped up by ad hoc purchases as necessary. We also take advantage of deals and offers, and certainly don't starve ourselves or stick to the bare basics.
That's now increased to about £120 per fortnight...