Prenatal and early childhood infections requiring hospitalization and risk of neurodevelopmental disorders in offspring: a population-based birth cohort study in Taiwan.

In utero and early childhood infections have been associated with an increased risk of neurodevelopmental disorders; however, the observed associations may be confounded by familial predispositions. This study examined the neurodevelopmental disorders attributable to maternal infections during pregnancy and early childhood infections during the first year of life, including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), tic disorders, and mental retardation (MR). We performed population and sibling comparison analyses to account for unmeasured familial confounding factors. We conducted a register-based cohort study with 2,885,662 individuals (comprising 1,864,660 full siblings) born in Taiwan between 2001 and 2018 and followed up until 2021. We employed Cox regression analysis to assess the association between in utero and early childhood infections requiring hospitalization and the subsequent risk of neurodevelopmental disorders. In the population analyses, an offspring exposed to maternal infection had an increased risk for ASD (hazard ratio (HR) = 1.19, 95% confidence interval (CI): 1.13-1.26), ADHD (HR = 1.14, 95% CI: 1.11-1.18), and MR (HR = 1.21, 95% CI: 1.13-1.30). These associations attenuated toward null in the sibling analyses. Individuals exposed to early childhood infection had an increased risk for ASD (HR = 1.13, 95% CI: 1.10-1.16), ADHD (HR = 1.16, 95% CI: 1.15-1.18), tic disorders (HR = 1.12, 95% CI: 1.09-1.15), and MR (HR = 1.64, 95% CI: 1.60-1.69) in the population analyses; these associations were also significant for ASD (HR = 1.14, 95% CI: 1.07-1.21) and MR (HR = 1.52, 95% CI: 1.44-1.62) in the sibling analyses. The association between maternal infection during pregnancy and offspring neurodevelopmental risk is largely due to familial confounding factors. Conversely, infection in early childhood may be attributable to it being a sensitive period and may play a role in the subsequent risk of ASD and MR.