TUESDAY, June 7 (HealthDay News) -- Being in a serious relationship is not enough to protect young gay men from infection with HIV, new research suggests.

In fact, a study by researchers at Northwestern University found that young gay couples are six times more likely to have unprotected sex than casual partners.

The researchers noted that gay men account for nearly 70 percent of all new HIV/AIDS diagnoses among adolescents and young adults in the United States. A recent study by the U.S. Centers for Disease Control and Prevention also found that the majority of new HIV infections occur within committed relationships.

"Being in a serious relationship provides a number of mental and physical health benefits, but it also increases behaviors that put you at risk for HIV transmission," Brian Mustanski, associate professor in medical social sciences at Northwestern University's Feinberg School of Medicine and the study's lead author, said in a university news release. "Men who believe a relationship is serious mistakenly think they don't need to protect themselves."

The researchers, who examined the behaviors of 122 men, 16 to 20 years old, over the course of two years, concluded that HIV prevention programs should be redirected toward serious relationships, not casual ones.

"We need to do greater outreach to young male couples," Mustanski said. "This is one population that has really been left behind. We should be focusing on serious relationships."

Mustanski pointed out that about 80 percent of gay young men who are HIV positive are unaware of their status because they aren't having themselves tested often enough.

"It isn't enough to ask your partner his HIV status," he said. "Instead, both people in a serious, monogamous couple relationship should go and receive at least two HIV tests before deciding to stop using condoms."

The study results were published online in Health Psychology.

More information

The U.S. Centers for Disease Control and Prevents has more on HIV/AIDS.