Same-sex couples who live together have worse health than married opposite-sex couples and similar health as opposite-sex couples who are living together (after adjusting for socioeconomic differences), according to a new study from researchers at Rice University. "Families, Resources and Adult Health: Where Do Sexual Minorities Fit?" is one of the first studies comparing the health of married couples, cohabitating opposite-sex couples and cohabiting same-sex couples. The study appears in the March 2013 Journal of Health and Social Behavior.

"Previous studies have indicated there are health disadvantages to living together versus being married, but almost no previous research has focused on same-sex couples," said Justin Denney, assistant professor of sociology, associate director of the Kinder Institute Urban Health Program at Rice and the study's lead author. "This study is one of the first to show that the mental and physical health disadvantages of unmarried couples living together may extend to same-sex couples."

Denney said the findings were somewhat surprising given that previous research documents a strong positive relationship between higher socio-economic status and good health. The study showed that cohabitating same-sex couples have greater socio-economic resources than both married couples and cohabiting opposite-sex couples. Same-sex couples have average household incomes of $10,000 more per year than married couples and approximately $18,000 more per year than cohabiting opposite-sex couples, and they have approximately one more year of education.

Denney said that their research showed that health disadvantages between the two types of cohabiting couples occur for different reasons. For opposite-sex cohabiters, health disadvantages are partially the result of lower socio-economic status; for same-sex couples, the causes of the health disadvantages are undetermined but are not tied to socio-economic status, he said.

"Our research shows that cohabitating opposite-sex couples have fewer resources than married opposite-sex couples and are less likely to share the resources that they do have (such as health insurance and bank accounts) that can be leveraged toward better health," Denney said. "However, the study shows that cohabitating same-sex couples are socio-economically advantaged and similar to married opposite-sex couples in their tendencies to share resources within a relationship that can positively impact health."

Bridget Gorman, professor of sociology at Rice and the study's co-author, said that given the socio-economic advantages of cohabiting same-sex couples, it's unclear why they report equally poor health as cohabiting opposite-sex couples and worse health than married opposite-sex couples. However, she theorizes that there are factors not measured in their study that could have a negative impact on the health of cohabiting same-sex couples.

"Based on previous research linking health to socio-economic status, one might expect cohabitating same-sex couples to report the best health," she said. "However, our survey has no direct measures of stress from discriminatory（有辨识力的） experiences and that may be playing a part that we can't assess."