WEDNESDAY, May 11 (HealthDay News) -- Naturally conceiving and giving birth to twins may be a sign of good health, new research suggests.

The study found that among women who were born in Utah in the 1800s, those who gave birth to twins tended to live longer than the mothers of singletons.

University of Utah researchers analyzed records on nearly 59,000 non-polygamous women in the Utah Population Database who were born between 1807 and 1899 and lived to at least age 50. Of those women, about 4,600 gave birth to twins.

Among women born before 1870, mothers who had twins had a 7.6 percent lower yearly risk of dying after age 50 than mothers who had one baby at a time. Among women born between 1870 and 1899, the risk was 3.3 percent lower for moms who had twins, although that was not statistically significant.

The study also found that mothers of twins had more children than normal, had a shorter interval between births, and were older when they had their last child.

"The prevailing view is that the burden of childbearing on women is heavier when bearing twins," senior author and demographer Ken R. Smith, a professor of family and consumer studies, said in a university news release. "But we found the opposite: women who naturally bear twins in fact live longer and are actually more fertile."

The finding that mothers of twins tend to live longer does not mean that having twins is healthy for women, Smith explained.

Indeed, the study did not look at women who died in childbirth or before menopause, but only those who reached at least age 50.

But the findings suggest that healthier women are more likely to have twins.

The study is published in the May 11 online edition of the journal Proceedings of the Royal Society B.

"This study has been able to identify -- and it's a fairly novel result -- another important factor that contributes to health and longevity in later years, namely, that women bearing twins appear to be healthier," Smith said. "That innate healthiness is contributing to their ability to have twins, and it is also contributing to their longevity."

Smith directs the University of Utah's Pedigree and Population Resource, which maintains and manages the Utah Population Database.

More information

The American Congress of Obstetricians and Gynecologists has more about twins.