New research has shown that men who start a family later in life are more likely to experience fertility problems and can increase the risk of health issues in their children.
The potential concerns over having children later in life have tended to focus on health risks associated with older women. However, the new study by researchers at Rutgers University in New Brunswick, New Jersey, has shown that men who delay starting a family until their late thirties (and beyond) can similarly experience fertility issues, while increasing the risk of health problems in both their offspring and partners.
'While it is widely accepted that physiological changes that occur in women after 35 can affect conception, pregnancy and the health of the child, most men do not realise their advanced age can have a similar impact,' said Dr Gloria Bachmann, director of the Women's Health Institute at Rutgers Robert Wood Johnson Medical School, who led the research.
The team advised men to consider freezing their sperm before the age of 35, if they plan to have children later in life.
Published in the journal Maturitas, their study reviewed 40 years of research investigating pregnancies involving older men. Although there is no clear definition of 'advanced paternal age', it is assumed to start between 35 and 45.
The team showed that men aged 45 years plus not only experienced decreased fertility, but put their partners at risk for increased pregnancy complications such as gestational diabetes, preeclampsia and preterm birth. This was the case even when the mothers were as young as 25.
Moreover, infants born to older fathers were found to be at higher risk of premature birth, late stillbirth, low birth weight, with a higher incidence of newborn seizures and birth defects such as congenital heart disease and cleft palate. There was also an increased likelihood of childhood cancers, psychiatric and cognitive disorders, and autism in later life.
The researchers attribute the elevated risks to both a natural decline in testosterone levels and age-related sperm damage that leads to a reduction in sperm number and quality. Mutations in the sperm DNA may contribute to disorders, including schizophrenia, in the offspring.
'Although it is well documented that children of older fathers are more likely to be diagnosed with schizophrenia – one in 141 infants with fathers under 25 versus one in 47 with fathers over 50 – the reason is not well understood,' said Dr Bachmann.
The number of older fathers is rising, with a 10 percent increase in fathers aged over 45 during the past 40 years in the USA.
The researchers advocated that doctors should counsel older men as well as older women of the realities and risks of having children later.