There seems to be a lot of discussion on economic incentives (harder to raise, stronger pensions and less personal involvement) and other modes of entertainment being the reason for this trend, but I wonder if it could be attributed to more understanding on proper upbringing and awareness of such, and self-doubt on people to meet that demands.

Maybe the TV and schooling discussed is indirectly related, such as better understanding of proper upbringing, or more ways to see how things can be messed up, and having larger support group beyond family (and children) for said women in poorer countries.

In general there is more focus put on raising a child better and more involvement beyond hedonistic, time or economic reasons and better parenting expected that some don't think they meet the needs or find it harder to do the same for more than one child.

This is a bit of extrapolating from a small anecdotal group, but I wonder how statistically significant said group is.