Divorce can have a severe impact on children -- hurting their performance in math, increasing their anxiety and short-circuiting their social skills -- but not necessarily as soon as families and family therapists expect it.

While research has shown that children struggle with divorce, a study released Thursday by the University of Wisconsin-Madison is one of the first to determine just when those struggles emerge.

Reviewing the test scores and social well-being of 142 grade-school children with divorced parents, researcher Hyun Sik Kim was surprised to find no significant decline in the months leading up to their parents' divorces.

It was only during the divorces themselves that struggles emerged.

And two years later, the children remained behind their classmates from two-parent homes.

"They do not recover fully," Kim said, "and they do not catch up with other children from intact families."

Kim's findings were not a surprise to Twin Cities' counselors and attorneys. For children, there's a difference "between parents just fighting, and fighting and divorcing," said Phyl Bean, a Bloomington lawyer.

"While the parents are still together, they've got predictability and some sort of stability, even though it's bad," she said. "Once the divorce has started, then they've really got to face that issue."

Kim found that in the fall of kindergarten, kids in the study whose parents would eventually divorce scored 3 to 4 points lower on standardized math tests. By fifth grade, when the children's parents had divorced, their math scores were 7 to 10 points lower than those of children from two-parent homes. There was no difference in reading scores.

Kim said a decline in math was more likely because a divorce could derail children's learning of key early concepts -- making it harder for them to grasp complicated math lessons later on.

Kim also found that children internalized more grief and anxiety during and after divorces, but weren't more likely to act out through fighting or aggression.

Baseball without dad

The findings sounded familiar to Karin, a divorced Twin Cities mother whose son is 10 and daughter is 5. (She asked that her last name not be used because of a restraining order against an abusive ex-husband.) Her son was in kindergarten at the time of the divorce and was affected in ways she didn't see at the time, she said. Her son has since struggled with depression.

"It's hard because you're in a very fragile state," she said. "You're still focusing on your pain and your issues, and you're exhausted. Even if you're not telling [your children] what's going on, they can sense it."

Reminders of living without a father are everywhere, she added. In youth baseball, her son hit the ball on his first try but didn't know what to do next and chased after the ball.

"As a woman, it never occurred to me that he's not going to know stuff like that," she said, "stuff most boys know."

Kim's study, published in the American Sociological Review, has limitations in that it is based on a decade-old database that examined only grade-school children.

Divorce can be hard on children of all ages, experts said, and can particularly frustrate adolescents as they figure out their own identities. Grade-school children can struggle because they are old enough to know what is going on, but too young to understand that they aren't alone, said Tamara Stark, director of youth and family services for Tubman, a Minneapolis-based counseling and support agency.

Stark said the key, whether separating parents are married or not, is to give children as much stability as possible -- letting them know they are still loved, that they still will attend school and see friends, and that other children like them have experienced divorces.

"A big part is the parents learning new ways to cope emotionally," she said, "so they're not bearing that burden on their children."

Jeremy Olson • 612-673-7744