Older Dads More Likely to Have Babies With Health Problems

Older fathers are more likely to conceive babies who have health problems, scientists have warned in a study.

To answer whether a father's age affects his child's health, researchers at Stanford University studied data on 40,529,905 births in the U.S. between 2007 and 2016.

Compared with babies with fathers aged between 25 to 34, those whose fathers were 45 or above were more at risk of being born prematurely; with a low birth weight; being admitted to a neonatal intensive care unit; or suffering from seizures. According to the study published in the BMJ, these infants also ranked lower on the Apgar score, which is used to measure the physical health of a newborn baby.

Mothers also appeared to be at greater risk, as those with older partners were more prone to gestational diabetes.

Babies with older fathers are more likely to have health problems at birth, according to researchers. Getty Images

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Dr. Michael L. Eisenberg, Director of Male Reproductive Medicine and Surgery at Stanford University School of Medicine, told Newsweek: "Given that half of a child's DNA comes from the father, we did expect to see some association with paternal age. However, we were surprised how many infant outcomes were related. In addition, the association with maternal diabetes was also surprising."

The results, however, do not prove that the older a man is the less healthy his child will be. Reasons for delaying childbirth may also carry negative consequences, the researchers highlighted. "However, it is a study of all U.S. births over this time period," said Eisenberg.

The authors of the study acknowledged their research was limited because it only used existing data. They said they were also unable to completely adjust their results to account for maternal age, particularly as this is generally similar to the father's. That made it difficult to separate the effects of maternal and paternal age.

Eisenberg stressed: "I think it's important to understand that the risks we are seeing are modest. So for an individual, the risk may not change much. However, at a population level, there may be public health implications of men and women waiting longer to conceive.

"While the oldest father ever is 96, this research suggests that the risk to child and mother may increase if fathers conceive later."

In a BMJ editorial on the study, Dr. Hilary K Brown, assistant professor Interdisciplinary Centre for Health and Society at the University of Toronto, highlighted that the average age men and women in developed nations have their first child has spiked in the past 40 years, to 35 and 40 years old for women and men, respectively. Mostly, researchers have investigated the potential negative effects of a woman's age on a foetus and baby, rather than paternal age.

Similarly to the researchers, Brown commented that despite the researchers' efforts to account for male and female parents being similar ages, the results could still be skewed.

But the study was still useful, she suggested. "Given that many couples might not be aware of the potential impact of paternal age on perinatal health, the current findings underscore the importance of including, in reproductive life plans, discussions of paternal age," said Brown.

The research comes after a study published in April suggested eating fast food could cause fertility issues in women.

The authors of the study, published in the journal Human Reproduction, urged women who want to get pregnant to not eat fast food too often. The conclusion was based on interviews with almost 5,600 women in Australia, Ireland, New Zealand and the U.K. between 2004 and 2011.