Noah Millman weighs in on the debate:

The easiest way to defend the proposition on the grounds of freedom isn’t to say that pro-natal policies lead to economic growth, but to say that the decision to have children is a profoundly important one for many people, a life-defining choice, and that it is also an economically burdensome one. It’s very simple redistribution, no different, in principle, from the progressive income tax, but it’s a redistribution scheme that accounts for the fact that some decisions are more fundamental than others.

Relatedly, Kevin Drum points out that increases in child tax subsidies haven't goosed the fertility rate.