The married, responsible parents are holding off on having more children. The unmarried are on the dole and are incentivized to have more children.
If the incentives were removed and the economy improved, more married parents would have more children.
It seems to me that that is the rational response to today's societal conditions. Why would anyone want to bring children into what appears to be a world that will be biased against people who want to be ambitious, hard-working citizens?