Researchers pooled 34 studies that compared people born very preterm or at very low birth weight, including an extremely preterm or extremely low birth weight group, against people born at or near normal birth weight or full term. Most people were assessed as children, with fewer studied as teenagers and only a small number as adults. The studies came from high-income countries, except for one from Brazil.
Looking at formal ADHD diagnoses across 12 studies (1,787 people), the preterm and low birth weight groups had about three times the odds of a diagnosis. The link was weaker for the very preterm group and stronger for the extremely preterm group.
Across 29 studies (3,504 people) that used symptom rating scales, the preterm and low birth weight groups scored higher for inattention, for hyperactivity and impulsivity, and for combined symptoms. The studies disagreed with each other a great deal on the symptom results, and this was not explained by factors like age or study quality.
The authors suggest that infants born prematurely need specific prevention and management to reduce the ADHD burden, without saying what those steps are.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Franz, 2017: odds of an ADHD diagnosis, preterm and low birth weight groups combined, odds ratio 3.04; very preterm group, odds ratio 2.25; extremely preterm group, odds ratio 4.05.
What the terms mean:
- Odds ratio compares the odds of an outcome between two groups. 1 means no difference, above 1 means higher odds, and below 1 means lower odds.
Source: Adelar Pedro Franz, Gül Ünsel‐Bolat, Hilmi Bolat, et al.. Attention-Deficit/Hyperactivity Disorder and Very Preterm/Very Low Birth Weight: A Meta-analysis. PEDIATRICS (2017). doi:10.1542/peds.2017-1645