student loans are a hit!

[Landroval]

Single motherhood is/was a social experiment, for the most part. Prior to the proliferation of the welfare state, single motherhood was a decision reserved for only the most volatile marriages. I wouldn't say that this is the biggest contributor to the trend, however.
Rather, the phenomenon is largely the result of a culture that glorifies and promotes alcoholism, premarital promiscuity, and Club Life as hallmarks of personal success, with children being born out of wedlock entirely cobstituting a much larger majority of single motherhood situations, than "failed marriages" do.