More men are delaying fatherhood, and new research suggests that might raise the risk of both birth complications and infant health problems.
When new fathers are aged 45 or older, there's an increased chance of preterm birth, infant seizures and even gestational diabetes in the mother, the study found.
"When you think about fertility, don't forget the father. Having a baby is a team sport, and fathers do play a role as well," said study senior author Dr Michael Eisenberg. He is director of male reproductive medicine and surgery at Stanford University School of Medicine in California.
"Men shouldn't think of their runway as unlimited. There may be some health implications from waiting," he said.
But men shouldn't panic either. Eisenberg said to think of the potential risks like you would the lottery. If you buy two tickets, you've doubled your odds of winning, but you still probably won't hit the jackpot. Likewise, if you increase your risk of birth complications or child health problems slightly, the chances are still good that everything will be OK.
Eisenberg and his colleagues started the study because more men are choosing to have kids at older ages. Almost one in 10 children are fathered by a man over 40, the researchers noted. Yet, scant research has looked at how dad's age contributes to the way a pregnancy progresses and to the health of the child.
The study looked at data from more than 40 million births between 2007 and 2016. For infants, the researchers looked at birth weight, Apgar score at five minutes, admission to neonatal intensive care, seizures and the need for postpartum antibiotics. In moms, the researchers looked at the incidence of gestational diabetes and preeclampsia (dangerously high blood pressure during pregnancy).
Mutations in sperm DNA
The researchers controlled their findings to account for the mother's gestational age. They also controlled for education level, marital status, smoking history and access to care.
The investigators found that the greater the father's age, the greater the risk of problems. Men aged 45 and older had a 14% higher risk of a child being born prematurely. Men who were 50 or older had a 28% increased risk of that outcome, the study authors said.
Dads aged 45 and older also had an 18% higher risk of having an infant who had seizures compared to fathers between the ages of 25 and 34. They also had a 34% higher risk of having a partner who had gestational diabetes.
Eisenberg said he can only speculate on why older dads might face these higher risks. He said there are some mutations in sperm DNA as men age, and those changes might impact the pregnancy and child. It's also possible that epigenetic changes that affect the embryo and placenta when there's an older father may also affect maternal health.
Maternal obesity a risk factor
Dr Anthony Vintzileos, chair of obstetrics and gynaecology at NYU Winthrop Hospital in Mineola, New York, said the study may open the way for more research on how dad's age may play a role in pregnancy and child health.
But, he was quick to point out that the study cannot prove a cause-and-effect relationship, only an association.
And as for the connection to gestational diabetes, Vintzileos expressed concern that the researchers weren't able to adjust the data to control for the mother's weight. Maternal obesity is a risk factor for gestational diabetes.
Both Eisenberg and Vintzileos said these findings shouldn't lead anyone to change their family planning or life plans. They also both emphasised that it's too soon to make any changes in clinical practice based on this study.
The findings were published online in the BMJ.
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