Raising a child alone may take a lasting toll, leading to poorer health and more struggles with daily tasks after age 50, according to a new international study.

Social safety nets and resources from extended families may blunt this effect in some countries more than others, and researchers found the association with poor health was strongest in the U.S., England, Sweden and Denmark, compared to southern European countries.

“We had anticipated that single mothers in the U.S. would do poorly given that so many single moms are poor or low wage workers and that the U.S. lacks most basic social protections for single mothers compared to other countries,” said lead author Dr. Lisa F. Berkman of the Harvard Center for Population and Development Studies in Cambridge, Massachusetts.

“What was surprising was that U.K. women did about the same as the U.S. single women,” and single mothers in Scandinavian countries seemed to be at risk as well, Berkman told Reuters Health by email.

Scandinavia has some of the stronger maternity leave and basic anti-poverty programs, but women there still had a tough time, she said.

“We suspect that the basic social protection was still very helpful to them but not sufficient to protect these women,” she said. “They still tend to be poorer than married mothers and it may be that their work situations were challenging and that their extended families were not as supportive as those in Southern European countries.”

Researchers used surveys of more than 25,000 women over age 50 about their marital and childbearing histories as well as their ability to complete daily activities like personal hygiene or instrumental activities like driving or shopping. The surveys came from three previous studies in 14 countries.

Single motherhood was defined as having a child younger than 18 while being unmarried – the researchers did not account for cohabitation.

One in three U.S. mothers reported being a single parent at some point before age 50, making it more common than among women in England (22 percent), western Europe (22 percent) and southern Europe (10 percent), but less common than in Scandinavia, where 38 percent of mothers said they had been single mothers.

In general, having been a single mother was tied to poorer health and disability after age 50, as reported in the Journal of Epidemiology and Community Health.

The risk of having trouble with daily activities in later life seemed to be highest in England and Scandinavia, where women with a history of being a single mother were 50 percent more likely than others to have health problems. In the U.S., single mothers were 27 percent more likely to have difficulties in later life.

That compared to risk increases of 9 percent in Western Europe, 13 percent in southern Europe and less than one percent in Eastern Europe.

Risks were also highest among women who had been single mothers before age 20 or who had cared for a child alone for at least eight years.

“Lone mothers report worse health compared to couple mothers in most societies, regardless of which measure of health is chosen; whether it is mental or physical health,” said Sara Fritzell of the Karolinska Institute in Stockholm, Sweden, who was not involved in the research.

“Our thought is that single mothers work very hard to take care of their children,” Berkman said. “They may do this at the expense of their own health- they may exercise less, eat more poorly, or work very hard in a stressful act of balancing work and family needs.”

Berkman and her coauthors suspect that in countries like Italy, Spain and France, families and communities may play a stronger role in sharing family caretaking activities.

“Many countries have formal social policies or informal social supports that may protect women from health risks,” but the U.S. has few options for maternity leave, childcare or social support, she said.

It is possible that women who became single mothers were in poorer health even before having children, Berkman noted.

“However, even though mothers with poorer health are slightly more likely to become lone, this cannot explain the major bulk of the excess risk of poorer health among lone mothers,” Fritzell told Reuters Healthy by email.

Single mothers may benefit from a wide range of social, economic and health protection policies, ranging from social programs that protect women from poverty to those that enable single mothers to participate in the paid labor force while taking care of a family, Berkman said.

“So far, when looking at older populations, there are too few single dads to examine this question,” she said. “In the future however, we should look at this.”