Men waiting until their 30s to have kids, but new moms are older too study finds

STANFORD, Calif. — Parents are getting older, particularly fathers, and not just as a byproduct of time elapsing, a new study finds.

Researchers at Stanford University conducted the first comprehensive analysis of all 168 million-plus live births in the U.S. from 1972 to 2015, finding that the average age of both newborns’ mothers and fathers has increased over the period examined.

“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,” says Dr. Michael Eisenberg, the study’s lead author and an assistant professor of urology at the university, in a press release.

Father holding newborn baby
A new study finds that most men wait to become a father until after they’re 30, while new moms are also putting off having children until later in life.

The average age of a father at the time of his child’s birth is now 30.9 years, compared to 27.4 years in the early 70s, representing a three-and-a-half year increase. In fact, by 2015, nine percent of expecting fathers were over the age of 40, while about one percent were 50 or older.

Different demographic factors provided a bit of variance, such as race and educational background.

Asian fathers of newborns, for example, were 36, on average; fathers with a college degree had a mean age of 33.3.

These findings mirror similar studies conducted in foreign nations.

Since older fathers tend to offer an increased chance of having offspring with genetic abnormalities, there are some dangers to the rising age of fatherhood.

“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,” says Eisenberg.

The benefits, however, may make up for many of the deficiencies— older fathers are more likely to have better jobs and good financial situations, possess a stable lifestyle, and live with their children.

Meanwhile, women are also holding off on motherhood until later in life, says Eisenberg.

Although mothers have a limited fertility window, they have even more so put off child-rearing, which is evidenced by how the average age gap between mothers and fathers fell by fourth-tenths of a year during the period examined. (Fathers are still 2.3 years older, on average).

“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,” says Eisenberg.

Due to parents delaying settling down, it would appear as if there could be less young people in society in the near future, which through the lack of able bodies, could hurt the economy.

In case you’re wondering, the youngest father examined in the study was 11 years of age, while the oldest was 88.

The study’s findings were published in the journal Human Reproduction.


  1. The youngest father was 11 years old? Maybe including a victim of rape by a female throws off the results. I’d think only voluntary parents would show a trend here.

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