What happened
JAMA Network Open published a binational cohort study of more than 2.5 million mother-child pairs in South Korea and Japan. The population analysis found a modest association between maternal influenza infection during pregnancy and offspring neuropsychiatric disorders, but that signal was attenuated and was not statistically significant in sibling-comparison analyses.
Why it matters
The study is a useful reminder that large associations can reflect family, genetic, socioeconomic or healthcare-seeking factors rather than a direct pregnancy exposure effect. It does not make influenza harmless in pregnancy; it sharpens how the neurodevelopmental claim should be read.
What to watch
Replication in other health systems, vaccination timing, severity of infection, trimester-specific analyses and whether future studies can separate fever, inflammation, treatment and underlying family-level confounding.
