From the abstract in the American Sociological Review:

"Despite high rates of nonmarital childbearing in the United States, little is known about the health of women who have nonmarital births. We use data from the NLSY79 to examine differences in age 40 self-assessed health between women who had a premarital birth and those whose first birth occurred within marriage. We then differentiate women with a premarital first birth according to their subsequent union histories and estimate the effect of marrying or cohabiting versus remaining never-married on midlife self-assessed health.

...Results suggest that premarital childbearing is negatively associated with midlife health for white and black women, but not for Hispanic women. We find no evidence that the negative health consequences of nonmarital childbearing are mitigated by either marriage or cohabitation for black women.

For other women, only enduring marriage to the child’s biological father is associated with better health than remaining unpartnered.