Men Can Parent Older than Women. Ain’t that Grand? Maybe Not!

There is no news in the knowledge that men remain fertile almost indefinitely. And in this blog, as well as our book, Enough of Us: Why we should think twice before making children, we discuss the jeopardies for babies of older mothers.

Now, research is indicating that being an older dad has its substantial risks as well. It turns out that because men generate new gametes (cells that unite with other cells to produce the fertilized egg—oh, what the hell—sperm) for each fertilization, the chances of the sperm having gene mutations increase as the years pass.

You may know that in the United States one of every 88 newborns is inflicted with one of the disabilities on the autism spectrum. That number has been rising dramatically over the past few decades. While it’s true that some of that increase is due to improved diagnostic capabilities —Cheryl’s own brother being an example of that—there are other contingencies that need to be considered.

Researchers in Iceland analyzed the genetic makeup of 78 families in which offspring had been diagnosed with schizophrenia or autism. It was random mutations in the DNA of the fathers’ sperm that were the primary source.

Women develop their eggs very early in life, so there is not a significant ongoing opportunity for mutations. But since men are constantly producing new sperm, the opportunities for mutation present at each occurrence of genetic copying that is part of the sperm production process.

The study found that a 20-year-old father typically produces 25 mutations in his child’s genetic makeup. By the age of 40, that average rises to 65. The Icelandic geneticist who conducted the study tells the Los Angeles Times that the trend toward later fatherhood is “very likely to have made meaningful contributions to increased diagnoses of autism in our society.” The University of Iceland researcher, Kari Stefansson, attributes between 15 and 30 percent of all incidents of autism to genetic mutations from older dads.

Even so, the risk of a man in his 40s producing a child with genetic disorders remains a relatively low one in 50. That liability grows with the father’s increasing age.

The questions remain, is gambling on the wellbeing of a newborn—or the adult it is to become—ethically responsible? At what odds is the gamble worthwhile? And isn’t it an increasingly problematic ethical question if the father takes that gamble to ever-higher levels by inducing pregnancy as he ages?