Low birth weight affects IQ into teen years

The effects of low birth weight on academic achievement persist well into adolescence, even among young people from relatively affluent backgrounds, a new study shows.

Low birth-weight children scored 3 to 5 points below normal birth-weight children on standardized academic achievement tests at ages 11 and 17, Dr. Naomi Breslau and colleagues from Michigan State University in East Lansing found.

Children's IQ test score at age 6 predicted later scores, for the most part, the team reports in the medical journal Pediatrics.

While the effects of low birth weight on intelligence are modest, they are real, and doctors should consider recommending early interventions and enrichment to help overcome them, Breslau told Reuters Health.

"It's very important that people don't think things simply go away," she said.

Breslau and her colleagues followed 394 children from inner-city Detroit and 379 children from the city's more affluent suburbs. About half of the children in each group weighed less than 2500 grams at birth.

The study found "stark gaps in achievement scores" between the urban and suburban groups, the researchers note, while differences within both groups between low birth-weight and normal birth-weight children were roughly the same.

At age 17, low birth-weight children were 50 percent more likely than normal birth-weight children to score below the mean of 100 on reading tests and 60 percent more likely to score below average on math tests.

Breslau noted that the study design allowed her team to isolate the effects of low birth weight from those of a less-advantaged environment on academic achievement.

While preschool enrichment programs designed to boost general intelligence will likely be enough to help LBW children from affluent backgrounds, Breslau said, they are not sufficient to address academic problems many poorer low birth-weight children face.

SOURCE: Pediatrics, October 2004.