CHICAGO – Just like new moms, new fathers can be depressed, and a study found a surprising number of sad dads spanked their 1-year-olds.

About 40 percent of depressed fathers in a survey said they’d spanked kids that age, versus just 13 percent of fathers who weren’t depressed. Most dads also had had recent contact with their child’s doctor — a missed opportunity to get help, authors of the study said.

Other studies have shown that kids who are spanked are at risk of being physically abused and behaving aggressively.

The researchers said spanking is especially troubling in children who are only 1, because they could get injured and they “are unlikely to understand the connection between their behavior and subsequent punishment.”

The study was released online today in the journal Pediatrics.

The authors analyzed data on 1,746 fathers from a nationally representative survey in 16 large U.S. cities, conducted in 1999-2000. Lead author Dr. Neal Davis said that was the most recent comprehensive data on the subject, and he believes it is relevant today. Depression among fathers is strongly tied to unemployment rates, which are much higher now than a decade ago, he said.

The men were asked about depression symptoms, spanking and interactions with their 1-year-olds, but weren’t asked why they spanked or whether it resulted in physical harm. Overall, 7 percent of dads had experienced recent major depression.