Older fathers pass down longer telomeres (pictured, in white), which means their children could live longer (Photo: Creative Commons)

Men who hold off on having children until they are older may be helping their kids in the long run, according to a new study, published Monday in the Proceedings of the National Academy of Sciences. Delaying fatherhood may lead to children who are "genetically programmed" to live longer.

Researchers studied telomeres -- caps on the end of chromosomes that shorten as a person grows older. Shorter telomeres are linked to early death and an increased risk of chronic diseases such as diabetes.

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"Men produce about 100 million sperm per day, while women produce all their eggs in utero and then no more are produced in their lifetime," Dan Eisenberg, study author and a doctoral candidate in anthropology at Northwestern University, told Fox News. "The way telomeres work is that they get a little shorter as the cell has to divide. But in actuality if we look at sperm in older men, the sperm have longer telomeres. But in the blood of older men, the cells have short telomeres."

The researchers found that older fathers pass down longer telomeres, which means their children could live longer. While they could not explain why the telomeres were longer in sperm than they were in the blood, the researchers attributed it to an enzyme called telomerase.

"The most prominent explanation is that an enzyme called telomerase - which helps to extend the length of telomeres - is active at high levels in the testes," Eisenberg told Fox News "This telomerase activity could progressively extend telomere length as men age. An alternative explanation is that the sperm progenitor (stem cells) which have shorter telomere lengths tend to die out as a man ages."

Some experts said the study is not conclusive and that more research needs to be done.

"The authors did not examine health status in the first generation offspring," Thomas von Zglinicki, an expert in cellular ageing at Newcastle University, told BBC News. "Very few of the studies that linked telomere length to health in late life have studied the impact, if any, of paternal age. It is still completely unclear whether telomere length at conception (or birth) or rate of telomere loss with age is more important for age-related morbidity and mortality risk in humans."

Although there may be benefits to delaying fatherhood, delaying motherhood could be dangerous.

The risk of having a child with Down syndrome increases markedly as a woman gets older, according to American Congress of Obstetricians and Gynecologists. At age 30, the risk of having a child with Down syndrome is one in 1,000. At 40, one in 100. At 45, the risk is one in 30.

Eisenberg told Fox News that he will look into further generations to see how pervasive this benefit is.

"Is this some sort of adaptive signaling - helping the father to adjust the biology of his child so it's better to meet demands of the environment?" he told Fox News. "That's our hypothesis, so we might be looking at what are other things aside from age that occur over a father's lifespan that he gives to his children."