There was a podcast I listened to a while back that indicated the opposite, the idea was that the better off people are, the less likely they are to have kids. One of the explanations I remember was that the better off people are, kids are just another competing thing that they can do. For example, if you are well off and can go travel for a long period of time, you might be more inclined to do that vs deciding to have kids. Another stat was that birthrates were higher for lower income people.
How do you explain the inverse correlation between income and the total fertility rate within and between nations?
To me it seems counterintuitive that having more money, or like you said about ability to secure a roof over ones head, would mean less chance of having kids but that seems to be a clear trend. Have you actually looked into it or you just making up bullshit?