Men Have Biological Clocks, Too

A newly published medical study finds that the older the father, the more likely a mother will miscarry.

A couple’s risk of having a pregnancy end in miscarriage appears to rise along with the father’s age, regardless of how old the mother is, researchers reported Monday. Their study, of nearly 14,000 women who were pregnant in the 1960s and 70s, found that the risk of miscarriage was 60 percent greater when the father was age 40 or older than when he was 25 to 29 years old. What’s more, age made a difference even for men in their 30s. Miscarriage risk was about three times greater when the man was between 35 and 39 years of age than if he were younger than 25. These risks were all independent of the mother’s age, a well-known factor in miscarriage, the researchers report in the journal Obstetrics & Gynecology.

The findings add to evidence showing that, like women, men have a biological clock. Although men continually produce new sperm and can father children even in their golden years, research shows that their fertility gradually declines starting at a relatively young age. Also, as with women, older fathers are more likely to have children with birth defects.

One recent study found that a man’s ability to have a child fades after the age of 40, similar to a woman’s fertility decline after age 35. Another confirmed that genetic abnormalities in sperm steadily become more common as men age. Miscarriages, particularly those in the first trimester, often occur because of genetic anomalies in the fetus, which may explain the risk tied to paternal age.

The current findings strengthen the belief that couples planning a family should consider not only the woman’s age, but the man’s as well, according to the study authors. “As child-bearing is increasingly delayed in Western societies, this study provides important information for people who are planning their families,” write the researchers, led by Dr. Karine Kleinhaus, who was with the Columbia University School of Public Health in New York at the time of the study.

In addition to the main finding, it is interesting is that the pregnancies studied happened decades ago. One wonders if changing conditions will alter the findings.

One on hand, people continue to delay childbirth, we’re more obese, and more likely to have both parents in the workforce much later into a pregnancy. One would think those things would lead to more problems. Conversely, we have significantly better prenatal care–including obsessing over vitamins, alcohol consumption, and the like–and are less likely to smoke than our predecessors.

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James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College and a nonresident senior fellow at the Scowcroft Center for Strategy and Security at the Atlantic Council. He's a former Army officer and Desert Storm vet. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. Wayne says:

    Something smells funny.
    I do not know if what they say is true or not. I have been getting more and more skeptical of so-call studies especially foreign ones. Why have they not say who did the study? Only what publication published it. It was done with Jerusalem women in one group and an unknown reference group. Why not publish the data for others to look at.

    It is a typical story of another sensational conclusion from a study without any underlining data. I care little about the conclusion of this study but dislike the way studies are reported. It is the Internet age. If the data supports the conclusion show it. There are so many B.S. studies anymore that it is hard to know which ones are legit.

  2. Herb says:


    Right on with your observations.

    The question that should be asked about all studies is,

    Who paid for the study ? and How much.

    I remember many years ago that a “Study” showed that cranberry’s were bad for you.