Babies whose fathers are 45 years old and over are more likely to be less healthy at birth, a study of more than 40 million deliveries has suggested.
The research, published in the British Medical Journal, found the children of older fathers were born 20.2g lighter, and had a 14% greater risk of low birth weight (2.5kg) than infants born to fathers aged 25 to 34.
Babies with fathers aged 45 or older had a 14% higher chance of being admitted to a neonatal intensive care unit.
They were also born on average 0.12 weeks earlier and were 14% more likely to be premature than those born to younger fathers, the study found.
Researchers at Stanford University in California assessed data on 40,529,905 live births that took place in the US between 2007 and 2016.
The researchers said the study was important because it offered rare insight into the impact a father’s age can have on a child, where women have for years been encouraged not to put off having babies due to concerns over health and medical complications.
They added that while the absolute risks of being an older father remain low, the findings “emphasise the importance” of including data on men when investigating the public health implications of rising parental age.
The report said: “A significant number of these negative birth outcomes were estimated to be prevented if older fathers had elected to have children before the age of 45 years.
“The risks associated with advancing paternal age should be included in discussions regarding family planning and reproductive counselling.”