MONDAY, April 14, 2014 (HealthDay News) -- Young fathers may be at increased risk of depression symptoms after their baby arrives, all the way through to the child's kindergarten, a new study suggests.

Researchers found that for men who become fathers in their 20s and live with their children, depression symptoms tend to rise during the first five years of the child's life.

Experts stressed that the findings don't mean that young dads are destined to be clinically depressed. The study didn't prove that early fatherhood causes depressive symptoms -- it only showed an association between the two.

"But this does show us a time period where fathers are at increased risk," said lead researcher Dr. Craig Garfield, an associate professor of pediatrics at Northwestern University Feinberg School of Medicine in Chicago.

The new research was published online April 14 in Pediatrics and in the May print issue of the journal.

Many studies have looked into the risk of postpartum depression for mothers, but research into fathers' mental health during this period is much newer, Garfield said. Studies so far suggest that 5 percent to 10 percent of new dads develop clinical depression after the baby arrives.

What's more, researchers have found that when fathers are depressed, children tend to have more behavioral problems and weaker reading and language skills.

It's not clear what role dads' depression plays in those problems. But "when parents thrive, children thrive," Garfield said, so both parents' mental health is important.

For the new study, Garfield's team used data from a long-running project that began following more than 20,000 U.S. teens in the 1990s. Every few years, the participants completed a 10-question screening tool on depression symptoms -- asking whether they felt unhappy, tired or disliked, for example.

Of the more than 10,600 young men in the study, one-third had become fathers by the time they were aged 24 to 32. And, Garfield's team found, dads' depression scores showed a clear shift over time.

Among fathers living with their children, depression scores rose by an average of 68 percent over the first five years of their child's life. Fathers who weren't living with their children showed a different trend: Their depression symptoms rose after high school, and then started to decline after they became fathers.