Children born with a significantly lower-than-expected birth weight tend to perform slightly worse in reading and addition at ages 14–15. This is the conclusion of researchers who analyzed data from more than 92,000 children in Norway. The findings were published in the American Journal of Obstetrics and Gynecology (AJOG).
The researchers analyzed children born between 37 and 41 weeks of pregnancy. Newborns were classified as having a low birth weight if their weight fell within the lowest 10% for babies of the same sex and gestational age. This approach helped distinguish low birth weight from normal differences between children associated with the length of pregnancy.
In the early years of primary school, children with low birth weight scored approximately 2.3 points lower in mathematics than their peers with normal birth weight. The difference persisted at ages 14–15, remaining close to two points. Reading scores were also slightly lower, although the researchers found no clear differences in English language test results.
"However, low birth weight alone does not mean that a child will necessarily experience learning difficulties. On average, differences in early development gradually narrowed by around age five, and the influence of the week of birth on school performance became almost negligible. For children with low birth weight, the association with academic achievement proved more persistent," the researchers explained.
One possible explanation, according to the scientists, lies in conditions during fetal development. Restricted fetal growth may be associated with problems such as placental dysfunction, which can affect the supply of oxygen and nutrients to the developing baby. Previous research has suggested that such factors may also influence brain development. However, the new study did not investigate this mechanism and cannot establish the cause of the observed differences.
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