Researchers are calling on US employers to provide health insurance to all partners after a study revealed that unmarried couples are less likely to have medical support and therefore more likely to suffer illness.

The study by the Williams Institute on Sexual Orientation Law and Public Policy released today documents unequal access to employment-based health insurance for same-sex and unmarried heterosexual couples.

It found that unmarried couples were significantly less likely to have health insurance than married people.

The authors concluded that the number of uninsured people in unmarried couples would drop significantly if employers offered health insurance to domestic partners. Additionally, it also found that employers would experience only a small increase in health insurance enrolment and costs if they offered partner coverage.

“Most Americans who are younger than 65 get health insurance through their own job or a family member’s job, so excluding employees’ partners from coverage puts unmarried couples at a big disadvantage.” said M.V. Lee Badgett, research director at the Williams Institute and co-author of the study.

“We found that 20% of people in same-sex couples are uninsured, compared with only 10% of married people or 15% of the overall population. Unmarried heterosexuals with partners are even worse off, with almost one-third uninsured.”

Michael Ash, co-author of the study and associate professor of economics at the University of Massachusetts Amherst said the scheme would not be an extra cost for employers, “Our study found that employers offering domestic partnership benefits would see only a small enrolment increase of 1.4% to 2.1% of its overall workforce and small enrolment increases mean very small cost increases.”

Ms Badgett noted that gay, lesbian, and bisexual people are at a particular disadvantage with regard to health insurance benefits, since they cannot legally marry a same-sex partner in any state except Massachusetts, and only a few other states offer some kind of legal recognition.

Brad Sears, executive director of the Williams Institute, said it makes good business sense to introduce health benefits, “When employers do not provide equal coverage for the important long-term, committed relationships of unmarried employees, those employees’ families are vulnerable to receiving poor or no health care.

“Offering domestic partnership benefits will bring about a decline in the number of uninsured people, reduced social costs, and an substantial increase in Americans’ health and well-being.”