We know that women are starting families later than ever before. We also know that as women get older, the biological clock sounds louder as time goes on. If couples are having their first child at 35, what happens when they want to have their second, third or fourth child?
It turns out men should also pay attention to age when it comes to having more children.
Babies born to older fathers may be more susceptible to health problems including preterm birth, low birth weight and breathing problems. And women who have children with older men may have increased health risks, too — particularly gestational diabetes.
The new study was published in the British Medical Journal.
While women’s fertility declines with age, so do men’s - perhaps not as sharply as women’s. But it takes longer to get pregnant. The chances of pregnancy and birth problems are also increased when dads are older.
Using data from the National Vital Statistics System, researchers analyzed the more than 40 million live births that occurred in the U.S. between 2007 and 2016 They sorted the fathers of these babies into five age groups — younger than 25, 25-34, 35-44, 45-54 and older than 55 — and looked at measures of infant health within each of these categories.
After accounting for things like the mother’s age and the parents’ health and demographic information, the researchers noticed an association between paternal age and likelihood of both child and maternal health problems. Significant associations began to surface around age 45, and the data suggest that the older the father, the higher the risks.
As the father’s age increased, so did the chances of the infant being born prematurely, having a low birth weight, or requiring medical intervention after delivery, such as assisted ventilation, admission to neonatal intensive care, or antibiotics.
When fathers were aged 45 years or more, their children had 14% higher odds of being born premature (less than 37 weeks) and their babies had a 14% greater risk of low birth weight than when fathers were aged 25 to 34 years.
Infants with fathers aged 45 years or more were also 14% more likely to be admitted to a neonatal intensive care unit, and 18% more likely to have seizures. In addition, the rate of childhood autism increases by 80% when dads conceive after age 45.
If the father was 55 years or older, newborns also tended to score less well on the Apgar test used to assess the health of a child at birth.
The number of first births to women older than 35 years has risen by about 2% annually since the 1970s, and the percentage of all births in the US to fathers aged more than 40 has doubled, to 9%, over the same period.