(USA TODAY) -- Excessive newborn crying, also known as colic, can be one of the greatest tests of a parent's love -- and sanity.

Though all babies cry, some wail inconsolably for hours.

Some infants cry because of painful gut contractions caused by gas or allergies, but the source of others' crying remains a mystery, to doctors and exhausted parents alike, says Mijke van den Berg, a child psychiatrist at Erasmus Medical Center in the Netherlands.

Although colic usually goes away on its own by the time a baby is 3 or 4 months old, it can lead frustrated parents to shake their infants. In extreme cases, that can cause irreversible brain damage, says pediatrician Lisa Asta of Walnut Creek, Calif.

Studies have suggested that the babies may be more likely to have colic -- often defined as crying three hours a day, at least three days a week -- if their mothers are depressed.

Now, researchers are asking whether colic also may be more common in children of depressed men.

It's a sensitive subject. "The last thing parents need is more guilt," Asta says. "These people are pretty strung out as it is."

Still, van den Berg says, it's important to identify fathers who need help, both for themselves and for their children.

So van den Berg and her colleagues looked at 7,600 babies and their parents, screening both mothers and fathers during pregnancy and following up two months after birth, according to the study in today's Pediatrics.

Van den Berg says the study probably underestimates the link between depression and colic. That's because parents who were depressed during pregnancy were less likely to complete the surveys.

It's unlikely the baby's crying caused men to be depressed, she says, given that the men were screened for depression before their children were born.

Still, she says, her study has several major limitations.

Parents weren't asked to keep daily diaries of times when babies cried. Instead, they were asked to recall how often their children cried.

As a result, parents may not have remembered the total amount of crying correctly -- especially if they were already depressed, says Asta, who wasn't involved in the study.

Though her findings suggest that researchers look more closely at the question, van den Berg says, her study is far from definitive.

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