Researchers found that people with kidney failure who were married or divorced (or separated) were more than 50 percent as likely to be placed on a waitlist for a new kidney as never-married people. Those who were married were also 28 percent more likely to receive the organ, relative to single people on the waitlist.

These findings make sense, Dr. Laura Taylor of the Johns Hopkins University School of Nursing told Reuters Health -- "being married tends to give you team support."

Many people on the waitlist for a new kidney are on dialysis, she said, which means they have to follow a complicated diet and medication regimen, and keep up with many appointments. A partner can help them with all of that, Taylor explained, keeping them healthier overall. That, in turn, makes them eligible to join the waitlist, and when an organ becomes available, they're in good enough physical shape to receive it.

With a partner to help, "you remain as healthy as possible on dialysis," said Taylor, who did not participate in the study.

This is not the first study to show that marriage seems to go along with better health. Historically, studies have found that married people as a group tend to be healthier than singles -- though recent research suggests the health advantage of marriage may be fading.

Still, people with spouses tend to live longer, be less depressed, and suffer less from cardiovascular disease. Every year, an average of 90,000 Americans develop kidney failure, at which point they must begin dialysis or receive a kidney transplant -- and if they receive a transplant, married patients tend to fare better than single transplant recipients.

To investigate whether marriage is linked at all to the odds of receiving a new kidney in the first place, the researchers looked at information collected in the U.S. national kidney failure database, focusing on the 3,650 people whose records included information about their marital status.

Approximately 56 percent of those with kidney failure were married, while 14 percent were divorced or separated, and 30 percent were either widowed or had never married.

The authors were unable to include information on single-sex relationships, whether single people had unmarried partners or the quality of marriages, they note in the American Journal of Transplantation.

It's not clear why married or divorced people may fare better when it comes to kidney transplants, study author Dr. Muhammad Khattak of Beth Israel Deaconess Medical Center and Harvard Medical School told Reuters Health in an e-mail.

Previous research has shown married people often have better access to healthcare, and better health overall, which may render them "more qualified candidates for renal transplantation." Although this study focused on kidney transplant, it's possible the same trend is true for other organs, he added.

Of course, it's also possible that healthier people may be more likely to get and stayed married, in which case marriage itself offers no benefit to getting a transplant, noted Khattak, also based at the University of Massachusetts Memorial Medical Center.

Twenty percent of donated organs came from so-called live donors -- living people who agreed to give up one of their kidneys. Here, too, being married can help, Taylor pointed out, since spouses may offer to donate a kidney. And even if a husband is not a match for his wife, they can enter a kidney "swap," Taylor explained, in which the husband gives his kidney to someone unrelated, which "sets off a chain reaction of donation swapping," and the wife receives a kidney from someone else.

Even people who are divorced may still be close with their spouses and the friends from when they were married, giving them a "complex social network that can be relied on," she added.