Although triplets are usually born early and smaller than other babies, they may be faring well by the time they are teenagers, a small study suggests.

The study, which followed 19 sets of triplets, found that by about age 14, the teens were in the "normal" range as far as health-related quality of life and behavior.

And they were faring no differently than 51 teenagers who were born as "singletons," but also at a low weight.

In fact, parents of triplets reported fewer behavioral issues compared with parents of singletons.

Dr. Giancarlo Natalucci and colleagues at the University Children's Hospital Zurich, in Switzerland, report the findings in the Journal of Pediatrics.

It's known that triplets are usually born prematurely and at low birthweight. And studies have found they are at greater risk than singletons of developmental delays early in life.

However, there's also evidence that any differences between triplets and their peers start to wane around the ages of five to seven.

Not much has been known about older kids, according to Dr. Rajan Wadhawan, an assistant professor of pediatrics at the University of South Florida in St. Petersburg.

"There are good studies that look at triplets' outcomes at two years of age, but not beyond," said Wadhawan, who was not involved in the current study but has researched triplets' development early in life.

In an email, Wadhawan said these latest findings suggest that, for triplets who do not suffer serious problems after birth, the long-term outlook seems good.

In his own recent study, Wadhawan found that triplets born at extremely low weights faced greater risks even compared with singleton infants born similarly small.

Those triplets were more likely to die or have neurological impairments like cerebral palsy, blindness or deafness before age two.

"The results of (the current) study are quite different from what we showed in our triplet study," Wadhawan said. "However, we studied a very different group of babies."

In this study, triplets' average birth weight was about three pounds, eight ounces; the newborns in Wadhawan's study all weighed less than two pounds, three ounces.

Natalucci's team followed 19 sets of triplets and 51 singletons, all matched for birth weight, into adolescence. At that point, the kids and their parents completed standard questionnaires on health-related quality of life -- a measure of things like physical health, emotional well-being and support from friends.

Parents and teachers also rated the teens' behavior, which included problems with "acting out" and "internalizing" issues like depression or withdrawal.

Overall, teachers rated the triplets and singletons similarly. But parents of triplets actually reported fewer behavioral issues.

The findings, Natalucci's team writes, suggest that triplets' outlook is "good" -- and in certain ways, they may fare even better than singletons born small.

Wadhawan agreed that there is some good news here for parents. "Although there are risks of prematurity in multiple pregnancies, and the possibility of serious morbidities in those born preterm," he said, "triplets who do not suffer from these issues may enjoy some benefits as compared to singletons at later stages."

Triplets and other "high-order" multiples are becoming increasingly common. Experts say that's partly because women are giving birth at older ages, but mostly because of fertility treatments that increase the odds of having more than one baby.

In the United States, there were nearly 6,000 triplets born in 2007. That compared with about 2,100 high-order multiples born 20 years earlier.