Dr. Eisenberg, Dr. Yash S. Khandwala and colleagues found that fathers older than 45 had a 14 percent greater chance than fathers in their 20s and 30s of their babies being born prematurely and at low birth weight. The mothers too faced a 28 percent increased risk of gestational diabetes. As the fathers’ ages rose, their babies were more likely to need help with breathing and require admission to the neonatal intensive care unit.

The risks associated with older fathers go beyond those obvious at birth. An earlier review of studies published by Dr. Eisenberg and Dr. Simon L. Conti, clinical assistant professor of urology at Stanford, linked paternal aging to an increased risk of babies born with congenital diseases like dwarfism or developing psychiatric disorders like schizophrenia and bipolar disorder and developmental ones like autism.

For example, a study of nearly 400,000 men and women born in Israel in the 1980s found that among fathers older than 40, the risk of having a child with autism increased nearly sixfold. Other studies found that the risks of childhood leukemia, breast and prostate cancers were elevated among offspring of older fathers.

Lots of attention has been paid to the risks women face by delaying pregnancy beyond, say, age 35, but men have not been privy to comparable concerns about their fertility and possible health effects on a pregnancy or the children they father. Older mothers are typically meticulously screened for possible risks to a healthy pregnancy “while the father’s role in childbirth is often ignored or forgotten,” Drs. Eisenberg and Khandwala wrote.

Although the risks of fathering a child in one’s 50s, 60s and 70s are not huge, the recent studies have shown there are sometimes significant long-term societal as well as personal consequences.

The challenges start with getting pregnant, which often takes longer when prospective fathers are older, Dr. Eisenberg told me. “Fertility is a team sport, and the runway for men is not unlimited,” Dr. Eisenberg said. A woman hoping to become pregnant by an older man might want to know “how good are your swimmers?” a question that can be answered by a semen analysis.

“The ability to father a child declines as men get older,” he said. “Semen quality diminishes — volume lessens with age and the motility and shape of sperm decline a little.” Such changes reduce the ability of a man’s sperm to fertilize an egg.