South Korea: A binational population-based birth cohort study in South Korea and Japan found that maternal influenza infection during pregnancy was associated with an increased risk of neuropsychiatric disorders in offspring. However, these associations lost statistical significance in sibling-comparison analyses, suggesting that shared familial or genetic factors may partly explain the observed relationship. Further research is needed to clarify whether maternal influenza directly contributes to neuropsychiatric outcomes in children.

The study, published in JAMA Network Open, was conducted by Jaehyun Kong, Department of Medicine, Kyung Hee University College of Medicine, Seoul, South Korea, and colleagues. The researchers examined whether influenza diagnosed during pregnancy was associated with subsequent neuropsychiatric conditions in children, addressing inconsistencies in previous evidence on the potential long-term effects of maternal infections.
The researchers used health insurance data from South Korea and Japan to investigate these associations, using population-level analyses and sibling comparisons to account for family-shared confounding factors.
The South Korean discovery cohort included 2,564,435 mother-child pairs, with a mean maternal age of 31.9 years. Among them, 35,973 children (1.4%) were exposed to maternal influenza infection during pregnancy. The Japanese replication cohort comprised 181,681 mother-child pairs, including 11,198 children (6.2%) exposed to maternal influenza.
Children born between January 2010 and December 2017 were followed until December 31, 2023. The primary outcome was the first postnatal diagnosis of any neuropsychiatric disorder, including severe neuropsychiatric disorders, obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and intellectual disability.
The researchers used statistical weighting to adjust for potential confounders and Cox proportional hazards models to estimate the association between maternal influenza and offspring outcomes. They also conducted analyses according to the trimester and season of infection.
The key findings were:
  • Increased population-level risk: Maternal influenza infection during pregnancy was associated with a 9% higher risk of any neuropsychiatric disorder in the South Korean cohort (adjusted hazard ratio [AHR], 1.09) and a 10% higher risk in the Japanese cohort (AHR, 1.10).
  • No significant association in sibling comparisons: After comparing siblings with differing prenatal exposure to influenza, the association was no longer statistically significant in South Korea (AHR, 0.98) or Japan (AHR, 1.04).
  • Potential familial influence: The attenuation of the association in sibling analyses suggests that shared familial characteristics, including genetic and environmental factors, may partly account for the relationship observed in the overall population.
The authors cautioned that limited statistical power in sibling analyses and wider confidence intervals may explain the loss of statistical significance. Other limitations included potential influenza misclassification, residual confounding from unmeasured genetic and lifestyle factors, and limited generalizability beyond Asian populations. The short follow-up may also have missed disorders emerging later in life.
The researchers concluded that familial factors may partly explain the observed association. Further studies with longer follow-up are needed to determine whether maternal influenza independently influences neuropsychiatric outcomes in offspring.
Reference:
Kong J, Hong S, Jo H, et al. Maternal Influenza Infection During Pregnancy and Neuropsychiatric Disorders in Offspring. JAMA Netw Open. 2026;9(10):e2637902. doi:10.1001/jamanetworkopen.2026.37902
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Article Source : JAMA Network Open

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Medha Baranwal

Medha Baranwal holds a Bachelor’s degree in Biomedical Sciences from the University of Delhi and a Master’s degree in Biotechnology from Amity University. Since May 2018, she has been contributing to Medical Dialogues, writing and editing medical news articles that translate complex research into clear, accessible information for healthcare professionals.

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