Hollywood star Robert De Niro has highlighted the health issues of becoming an older dad after revealing he has fathered his seventh child at the age of 79.
While De Niro said that parenthood “never gets easier”, the Godfather actor – whose first child was born in 1971 – said he was “good with it”, after being asked about the news at a New York premiere.
The actor is far from the only celebrity to have had a child in older age, with musicians Mick Jagger and Billy Joel both among those to have become new fathers aged 72 and 68 respectively, and less recently silent film legend Charlie Chaplin at the age of 73.
Across the population in the UK, the typical paternal age has been increasing for years, with the average first-time father found to be 33.7 years old in 2021.
But while some men remain fertile all their lives, studies have found a number of health risks associated with fathering children at an older age.
An “exhaustive” review of studies into the matter, published in the US government’s National Library of Medicine in 2015, described “disturbing links between increased paternal age and rising disorders in their offspring”.
According to the study, “increasing paternal age has shown to increase the incidence of different types of disorders like autism, schizophrenia, bipolar disorders, and childhood leukemia in the progeny”.
The risk of male infertiliy also rises among older men, who were found to have a lower IVF success rate and higher rate of preterm births, which can bring a greater risk of complications.
“One of the main risks that we see a lot of at the moment is the DNA fragmentation,” said Dr Bryan Woodward, a consultant reproductive scientist at the X&Y fertility clinic.
“As you get older, we know that the DNA starts to fragment in sperm – so it’s not just in female fertility that you get a decline, you also get a decline in male fertility,” Dr Woodward told The Independent.
“This means you could have a really good concentration of sperm, very good movement … [but] if you delve a little bit deeper, you often find that the chromatin – the genetic material – might be a little bit fragmented, and of course that can lead to problems going forward”.
However, problems in the sperm of older men may be offset by having a younger partner, he suggested.
Asked about the potentially heightened chance of conditions such as schizophrenia and childhood leukemia among children born to older fathers, he said: “As you get older, your DNA is less competent, so one would assume you’re going to get more diseases linked to possible problems in the DNA.
“But if you have a younger partner, often those DNA problems may be resolved because the DNA can be repaired within the egg once the fertilisation takes place.”
Dr Woodward added: “What you find with older celebrities such as Mick Jagger and Robert De Niro is that, when you have a younger egg – so if your partner’s, say, in their 20s or 30s – then a lot of the machinery within the egg may help to repair DNA issues in the sperm.”
While studies suggest that children born to older fathers may be at increased risk of genetic disease, Dr John Parrington, of the University of Oxford, believes the link to be “very subtle” and hard to quantify, given that there are “so many other factors” influencing foetal development.
While there is “a much higher risk of infertility” among women over 35, and a greater risk of pregnancy complications, miscarriages and a “clear link with Down’s Syndrome”, Dr Parrington told The Independent that age-related fertility issues are not “anywhere near as clear” for men.
Aside from the menopause, “one huge difference between men and women is that women’s eggs are actually formed when they are still in the foetal stage”, added Dr Parrington, an associate professor in cellular and molecular pharmacology.
This means that a 35-year-old woman’s eggs “are actually 35 years old”, whereas men constantly produce new sperm, meaning they’re “much newer cells”.
“So although there is an increased risk of genetic disease, it seems to me very subtle really. It’s something to be aware of if you are an older father but I don’t think it’s the sort of thing where you would say, ‘oh definitely don’t conceive at that age’,” he added.
“Because I don’t think we’ve got enough evidence that that is the critical thing. There’s so many more effects on foetal development of say, the environment, poverty, all these things – you’d have to weigh that up versus the genetic risks.”
He added: “There’s evidence that anxiety and stress in mice can be passed on to offspring via the sperm, so I guess it would also depend quite a lot on what’s happened to a person in their lifetime – how stressed they’ve been, how anxious, what sort of life they’ve had,” he said.
“That could all equally have an impact on progeny as well as ... [DNA] mutations.”
