The children of older fathers scored lower than the offspring of younger fathers on I.Q. tests and a range of other cognitive measures at 8 months old, 4 years old and 7 years old, according to a study released this month that added to a growing body of evidence suggesting risks to postponing fatherhood.

The study is the first to show that the children of older fathers do not perform as well on cognitive tests at young ages. Although the differences in scores were slight and usually off by just a few points on average, the study’s authors called the findings“unexpectedly startling.”

“The older the dads were, the slightly worse the children were doing,”said Dr.John J.McGrath, the paper’s senior author and a professor of psychiatry at the Queensland Brain Institute in Brisbane, Australia.“The findings fit in a straight line, suggesting there may be some steady beat of mutations happening in the dad’s sperm.”

The new study, published March 9 in the online journal PLoS Medicine, reanalyzed data from the federally sponsored Collaborative Perinatal Project, which gathered information from more than 50,000 pregnant women seen at 12 university clinics in the United States from 1959 to 1965.

The researchers analyzed the scores of 33,437 children who had been tested at regular intervals in a variety of cognitive skills . Fathers in the study were age 14 to 66, while mothers were 12 to 48.

Children whose fathers were 50 years old had lower scores on all tests, except those assessing physical coordination, than those whose fathers were 20, the researchers found. And the older the fathers, the more likely the children were to have lower scores, they found.


RONI CARYN RABIN