The study, which also states that having a child as a young single woman lowers economic status in midlife, appeared in the September issue of the Journal of Health and Social Behavior.
"Being unmarried at the time of first birth is associated with lower midlife income and a lower probability of being married in midlife. 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," study author John Henretta at the University of Florida said.
Data from the Health and Retirement Study was evaluated by Henretta, 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.
The data evaluation 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 reporting having heart disease, lung disease and cancer.
With the help of data evaluation, 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 can relate to poorer access to healthcare.
"The conditions under which a woman has a child at a young age would be important to consider," Ken R. Smith, a professor of human development and family studies at the University of Utah said.
"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?".
"But overall, this [study] is a plausible finding and worth replicating. A parallel study of men would be useful to determine if the effects exist for the fathers as well," Smith added.