Washington, Dec 5 (IANS): Lower weight at birth has an adverse effect on children's performance in school which is likely due to the early health struggles small babies often face, a research has found.

The researchers used a unique set of data that matched birth and school records from 1.6 million children.

The higher the weight at birth, the better the children performed in reading and math tests at school.

"We tend to think that good schools are places where struggling kids get special attention and motivated teachers can correct any problems with learning," said Jeffrey Roth, professor of paediatrics at the College of Medicine, University of Florida and co-author.

"This research indicates that it's not always the case. Good schools are good for everyone, but even the best schools don't seem to differentially help kids with early health disadvantage," Roth explained.

These findings held true when socioeconomic and demographic factors were equal among children's families, Roth said.

When researchers compare children with similar family backgrounds, birth weight plays a key role in predicting future school success.

"Children with higher birth weight enter school with a cognitive advantage that appears to remain stable through the elementary and middle school years," researchers said.

"The estimated effects of low birth weight are present for children of highly educated and poorly educated parents alike, for children of both young and old mothers, and for children of all races and ethnicities, parental immigration status, parental marital status and other background characteristics," the team concluded.

The study's results were published in the journal The American Economic Review.