Women who have their first child before age 20 are at a higher risk of chronic diseases and death when they reach middle age, a new study shows.

The study appears in the September issue of the Journal of Health and Social Behavior and reveals that women who are single at the time they have their first baby could also be at risk of earlier death — an outcome that probably relates to socioeconomic status later in life after having a child as a young, single woman.

“Being unmarried at the time of first birth is associated with lower midlife income and a lower probability of being married in midlife,” said study author and sociologist John Henretta at the University of Florida. “It’s not so much the characteristic of being unmarried at first birth that’s important; it’s what being unmarried at first birth tells us about the midlife status of these women.”

Henretta evaluated data from the National Institute of Aging’s Health and Retirement Study, focusing on 4,335 women born in the United States between 1931 and 1941. These women were first interviewed in 1992 (at ages 51 to 61) and then followed until 2002. Interviewers asked about their health, level of education, marital status, wealth, how many children they had and the age of each living child.

Study data showed that women who give birth before age 20 have a risk of dying 1.42 times higher than that of women who first give birth after age 20. Women who had a child before age 20 also had higher rates of heart disease, lung disease and cancer.

Henretta said that having a baby while unmarried could lead to a lower chance of eventually marrying and lower economic status in midlife, which research shows is associated with less access to healthcare.

“The conditions under which a woman has a child at a young age would be important to consider,” said Ken R. Smith, a professor of human development and family studies at the University of Utah. “For example, were her parents or siblings there to assist in rearing the child, did the child survive, did the mother go on to marry the father and was that first child followed quickly by another birth? (where should the close quotes be?)

“But overall, this [study] is a plausible finding and worth replicating,” Smith added. “A parallel study of men would be useful to determine if the effects exist for the fathers as well.”

The Journal of Health and Social Behavior is the quarterly journal of the American Sociological Association.

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