Is it safe for older fathers to have children?

In high-income societies a mix of social, economic and cultural factors are pushing more people to become parents at an older age thus increasing the chances of health problems.

Though older women are often reminded of the risks a late pregnancy poses to themselves and their babies, men past 40 should know that their age can also have a negative effect on babies’ health.

In most countries, including in the Asia-Pacific, the age at which couples start families has been rising over the past 40 years. While a woman’s clock typically slows in her 30s and runs down by age 50 or so, it can go on ticking almost indefinitely for a man. But is fathering later in life safe?

A recent study of more than 40.5 million births in the United States revealed potentially harmful effects from older fathers, such as risk of prematurity, low birth weight, low Apgar score, and seizures. Apgar stands for appearance, pulse, grimace, activity, and respiration and is a measure of an infant’s health.

The study, published in the British Medical Journal (BMJ) and directed by Dr Michael Eisenberg, an urologist and head of male reproductive medicine and surgery at the Stanford University School of Medicine, concluded that “more than 12 percent of births to fathers aged 45 years or older with adverse outcomes might have been prevented were the fathers younger.”

The study found that fathers older than 45 had a 14 percent greater chance of their babies being born prematurely and at low birth weight. The mothers too faced a 28 percent increased risk of gestational diabetes, or high sugar levels during pregnancy. As the fathers’ ages rose, their babies were also more likely to need help with breathing and require intensive care.

Earlier research found other risks that go beyond those that occur at birth. For example, studies have linked paternal ageing to an increased risk of babies born with congenital diseases like dwarfism or developing psychiatric disorders like schizophrenia and bipolar disorder and developmental ones like autism.

An Israeli study in the 1980s found that the risk of having a child with autism increased nearly sixfold with older fathers, while other studies linked higher risks of childhood leukaemia, breast, and prostate cancers with older fathers.

Older mothers are typically carefully screened for possible risks to a healthy pregnancy, “while the father’s role in childbirth is often ignored or forgotten,” the researchers wrote.

Obviously, one of the biggest challenges is getting pregnant in the first place, which often takes longer when the prospective father is older.

“Fertility is a team sport, and the runway for men is not unlimited,” Dr Eisenberg told The New York Times. “The ability to father a child declines as men get older. Semen quality diminishes — volume lessens with age and the motility and shape of sperm decline a little.”

But why are older fathers potential medical risks? Unlike women, who are born with all the eggs they will ever produce, after puberty men continuously produce new sperm. Mutations can occur and accumulate in the DNA, and environmental exposures can change the genes in sperm themselves. Some of those changes can affect growth factors for both the placenta and the embryo, Dr Eisenberg explained.

The researchers recommended that prospective parents adopt healthy lifestyles that can “pay off in a number of ways, not just in having a healthy pregnancy but also in preventing chronic disease. Physicians should be having these conversations with men, not just women.”