Cost of child-rearing

According to this NY Times column, the cost of raising a child, in monetary terms, is close to $2 million. I find it a rather dubious figure, when you consider that it attempts to factor in such things as what work you'd be doing if you didn't have a child. Who really knows? It also presents an absolute cost for one child that would not apply to the marginal cost of having a second child. And there's this:

To estimate the cost of housing a child, I subtracted our rent from the rent we would pay to live in our neighborhood in a more suitable space — one with higher security, a more responsive landlord, reliable heat and better stroller-accessibility. 

Maybe. Or maybe, like some people, you ended up buying a house because you had or would have children, and then maybe that house appreciated in value so you ended up wealthier than if you'd rented throughout your life. Or maybe it didn't. The counterfactuals involved put some pretty big unknowns into the calculation.