News ID: 199854
Published: 0617 GMT September 03, 2017

Huge discovery about Dads stuns scientists

Huge discovery about Dads stuns scientists

A fascinating new study out of Stanford University Medical Center has found that the average age of new dads is creeping up consistently, and that may be a good thing.

The study, published in the journal Human Reproduction, examined how the ages of first-time fathers have changed between 1972 and 2015 in the United States, and have found out that the mean parental age has increased from 27.4 to 30.9, wrote.

The findings, based on 168,000,000 births, also found that fathers who are older than 40 now make up nine percent of first-time fathers, and nearly one percent of those older than 50 are first-time dads. And because people who have children at an older age tend to be more financially and emotionally stable, this could be a boon for the children themselves.

In addition, older men are more likely to live with their kids and be heavily involved in child rearing. There are risks to children with older parents, however, such as autism, chromosomal abnormalities, and certain types of cancers and genetic conditions. But the benefits may outweight the positives.

The full statement from the university follows below.

The average age of newborns’ fathers in the United States has grown by 3.5 years over the past four decades, according to a new study from investigators at Stanford University School of Medicine.

Men over the age of 40 now account for about nine percent of all US births. Men over the age of 50 account for nearly one percent.

Those statistics come from the Stanford study, which is the first comprehensive analysis of all live births reported to a federal data depository in the United States from 1972-2015: To be precise, 168,867,480 births.


The Stanford researchers obtained the data from the National Vital Statistics System, an intergovernmental data-sharing program sponsored by the federal Centers for Disease Control and Prevention.

Michael Eisenberg, MD, an assistant professor of urology, is the senior author. The lead author is Yash Khandwala, a medical student at the University of California-San Diego who was a research scholar in Eisenberg’s lab at Stanford when the analysis was done.

The National Vital Statistics System records births and deaths reported by all 50 states, as well as self-reported maternal and, where available, paternal ages, levels of education and race and ethnicity of the parents. While the CDC periodically produces reports on maternal statistics, little information about newborns’ dads has been available.

Between 1972 and 2015, the researchers found, the average paternal age at the time of an American child’s birth grew from 27.4 years to 30.9 years. Asian-American dads — and in particular, Japanese- and Vietnamese-American dads — at upwards of 36 years of age, on average — are the oldest. Paternal age rose with more years of education; the typical newborn’s father with a college degree is 33.3 years old.

Over the same time period, the share of newborns’ fathers who were older than 40 doubled from 4.1 percent to 8.9 percent, while the share who were over 50 rose from 0.5 percent to 0.9 percent.

Similar trends of increasing age have been reported in other industrialized countries.

The steadily advancing age of newborns’ fathers is likely to carry public-health implications, Eisenberg said. A rising paternal age can affect the total number of children a man will have, which can impact the demographics of the population. In addition, he said, “every potential dad acquires an average of two new mutations in his sperm each year. And there are associations between older fatherhood and higher rates of autism, schizophrenia, chromosomal abnormalities, some pediatric cancers and certain rare genetic conditions.”


On the flip side, he noted, older fathers are more likely to have better jobs and more resources, more likely to have reasonably stable lifestyles and more likely to live with their children and, thus, be more involved in child-rearing.

“Maternal ages at birth have been increasing, too,” Eisenberg said. “In fact, they’ve advanced even more than paternal ages have in the same time frame. This may be a consequence of women waiting longer to get married or putting off childbearing as the years they spend in higher education increase and as careers become more central to their lives. The result is that the average age difference between moms and dads has been shrinking, from 2.7 years in 1972 to 2.3 years in 2015.”

This convergent pattern appears to apply to all racial, regional, age and education categories, he said. “We’ve seen a lot of changes in the last several decades. Contraception is more reliable and widespread. Women have become more integrated into the workforce. This seems to be reflected in an increasing parity in parental ages over the last four decades.”

Advancing parental age leaves fewer years for childbearing and is likely to exert a follow-on effect of reducing the average family size over the long haul, with potentially huge economic ramifications, Eisenberg said.

“Fewer people being born means fewer productive workers a generation down the road,” he said. “This can obviously have profound tax and economic implications.”

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