>"Teen pregnancy" makes sense because it's directly measurable/not easy to fudge and definitely has association with poorer outcomes for baby AND mother. The trouble is that while US teen pregnancy rates remain high, there has been a 63% decrease since 1991- which is no good for a graph purporting to blame the "war on poverty."
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>IMHO if you can eliminate the social disadvantage, differences in outcome boil down to Mom’s education level.

and the unwillingness to get an abortion - which will correlate in itself with religion and education
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>Followed by mother's age. Older is better so if single mothers are getting older, that should be good news.

I am not so certain that the growing trend of 45+ year mothers and (mother+x) fathers is that much better, even if monetary issues are less.