In states where same-sex marriage is not legal, laws may prevent partners from receiving health coverage. But while that in itself is an issue that gay rights groups are dealing with, such laws also affect a far more helpless crowd: their children. According to a new study, children with gay parents are less likely to have private health insurance than children of a heterosexual couple.

“Gay and Lesbian families face unique challenges that directly impact the health of their children, particularly health-related outcomes associated with health insurance,” they wrote, according to MedPage Today.”

The researchers found that 63.3 percent of children with two fathers and 67.5 percent of children with two mothers were covered by private health insurance, compared to 77 percent of children with heterosexual parents. When they compared parents’ incomes and educations, they found that kids with gay parents were 39 to 45 percent less likely to have private health insurance, compared to heterosexual parents’ children. Additionally, about 10 percent of children with two fathers were uninsured, compared to seven percent of children with two mothers, and less than seven percent of children of heterosexual parents.

“We’re fairly certain from past research that access to health insurance does directly affect children’s health,” lead researcher Gilbert Gonzales, a Ph.D. candidate in health policy and management at the University of Minnesota, told HealthDay News. The researchers say their results “provide supporting evidence in favor of recent policy statements by the [American Academy of Pediatrics] endorsing same-sex marriage and second parent adoptions.”

The results were very different in states that allowed same-sex marriage and adoptions. They found that the gaps in coverage closed for families with two mothers and same-sex adoptions, yet although families with two fathers saw a closed gap, it wasn’t as close.

The study looked at respondents to the 2008-2010 American Community Survey, which is conducted by the U.S. Census Bureau. The survey, which identified same-sex couples when a respondent labeled their partner as husband, wife, or unmarried partner, found that about 125,000 same-sex couples were raising 220,000 children.

There are already 13 states and the District of Columbia that allow same sex marriage, with another six that recognize civil unions or domestic partnerships. Eighteen states also allow same-sex adoptions.

“”I think we are going to see more and more research like this that shows how marriage-equality laws have far-reaching health consequences,” Richard Wight, a researchers at the University of California, Los Angeles, told HealthDay. “Increasingly, research is demonstrating that laws legalizing same-sex marriages are advantageous to health.”

Source: Gonzales G, Blewett L. Disparities in Health Insurance Among Children With Same-Sex Parents. Pediatrics. 2013.