DEAR MAYO CLINIC: How does paternal age affect fertility? Can the age of the father have an impact on the baby’s health?
ANSWER: Age can have an effect on a man’s fertility. But the influence of aging on fertility in men is not as significant as it is in women. Research has shown that there may be an increase in the risk for certain health problems in the children of older fathers. The risk, however, appears to be small.
After puberty, most men produce sperm throughout the rest of their lives. That means men can conceive a child well into their later years. That said, studies have shown that men who are older than 40 tend to be less fertile than younger men. But even though older age does reduce fertility, a man’s age alone does not seem to have a substantial effect on a couple’s fertility overall. For example, studies have shown that a man’s age does not decrease the success of fertility treatment in couples who seek those services.
A man’s age at the time a baby is conceived is called his paternal age. A woman’s age at conception is maternal age. A woman’s maternal age is considered to be advanced and health risks for a baby increase after age 35. There is no universally accepted definition of when paternal age is considered to be advanced. Various studies have used cutoffs of 40, 50 and even 60 years for advanced paternal age.
There is no one clear point at which health risks for a baby start to increase with older fathers because the risk grows very slowly over time. The more times a man’s body has created sperm — a process called spermatogenesis — the more of a risk there is for chromosomal abnormalities. This may be part of the reason why there is an increased risk for certain genetic disorders, such as a form of dwarfism known as achondroplasia, in infants of men older than 40.
The potential for other possible health risks have been identified in children of older fathers, too. Research has found that children born to men 40 and older seem to be more likely to develop autism than children of men younger than 30. Children born to men 50 and older appear to be at an increased risk for the brain disorder schizophrenia when compared to children of men younger than 25.
The risk of cognitive impairment also might be higher for children of older fathers. In a 2009 study, children born to older men scored slightly lower on tests measuring concentration, memory, reading and reasoning skills through age 7.
Despite the increase in these risks, however, the overall likelihood for a baby to be born with health problems just because a father is older is still quite low.
If you are older than 40 and you are considering fathering a child, it may be useful for you to have a conversation with your health care provider. He or she can review your medical history and family history to see if there may be any concerns regarding your fertility or health risks for the baby, as well as discuss your reproductive health overall. — Jani Jensen, M.D., Reproductive Endocrinology & Infertility, Mayo Clinic, Rochester, Minn.