If your kindergartner is hyperactive, there's no reason to blame the caffeine you had during pregnancy, new research suggests.

In a study of more than 3,400 five- and six-year-olds, reported in the journal Pediatrics, researchers found no evidence that the children's behavioral problems were related to their mothers' caffeine intake during pregnancy.

The odds of hyperactivity, inattention or other issues at home or school were not raised among kids whose moms had downed more than 425 milligrams of caffeine per day during pregnancy. That's roughly equivalent to the amount in three cups, or 24 ounces, of coffee a day. But that doesn't mean caffeine is completely in the clear, according to Eva M. Loomans, of Tilburg University in the Netherlands, who led the study.

For one, the researchers did not look at any other developmental issues besides problem behavior, she told Reuters Health in an email. And only a few studies have looked at the question of whether caffeine during pregnancy affects children's later behavior - with mixed results.

For now, Loomans suggested that pregnant women follow the advice of their doctors on caffeine intake. The issue of whether it's OK to have some caffeine during pregnancy has often been confusing.

Over the years, some small studies suggested that caffeine may be linked to the risk of miscarriage or preterm birth. But more recently, larger studies have failed to show any heightened risk.

And in 2010, the American College of Obstetricians and Gynecologists (ACOG) said that 200 milligrams of caffeine a day - about the amount in a 12-ounce cup of coffee - probably did not carry pregnancy risks.

But the question of whether mom's caffeine could affect her child's development in some way remains. So far, there's little evidence that it does. Instead, much of the concern comes from animal research - which has suggested caffeine can affect fetal brain development in a way that alters behavior later in life.

Whether that's true for humans is unknown.

In this study, prenatal caffeine did not appear to be related to "problem behavior."

The research involved 3,439 Amsterdam children whose mothers had completed detailed questionnaires on lifestyle and other factors during pregnancy. When the children were between the ages of five and six, their moms and teachers were surveyed about behavior problems.

Overall, about five percent of kids had some type of behavioral problem, like hyperactivity or inattention. But the risk was no greater for kids whose moms downed big daily doses of caffeine.

Still, that is not a green light to have all the caffeine you want during pregnancy. Based on the ACOG advice, moderation is key. And Loomans cautioned there is still more to be learned about caffeine and kids' long-term development.

This study could only look at the overall relationship between mothers' self-reports of caffeine intake and their reports on their children's behavior. That does not necessarily mean caffeine has no effects, at least for some kids, according to Loomans.

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