Context: The link between congenital hypothyroidism (CH) and neurodevelopment is suggested, yet studies applying quantifiable measures are lacking. Moreover, socioeconomic disparities and subtle variation in timing of approach make the relationship difficult to detect. Objective: To evaluate associations between CH and abnormalities in neurodevelopment and growth and determine the critical period for intervention. Methods: We utilized a nationwide database to conduct a longitudinal analysis of 919 707 children. Exposure to CH was identified using claims-based data. The primary outcome of interest was suspected neurodevelopmental disorder, as measured using the Korean Ages & Stages Questionnaires (K-ASQ) administered annually from 9 to 72 months of age. Secondary outcomes were height and BMI z-scores. After randomly matching cases and controls at a 1:10 ratio, we employed inverse probability of treatment weighting and generalized estimating equation models for our analyses. We conducted subgroup analysis based on the age of treatment initiation. Results: The prevalence of CH in our population was 0.05% (n = 408). Relative to the control group, the CH group had higher risk of suspected neurodevelopmental disorders (propensity score–weighted odds ratio: 4.52; 95% CI: 2.91, 7.02), and significantly increased risk in each of the 5 K-ASQ domains. No time interactions were noted at any rounds for the outcomes according to when the neurodevelopmental assessment was conducted (all P for interaction >.05). The CH group also had higher risk for low height-for-age z-score, but not for elevated BMI-for-age z-score. In subgroup analysis, delayed medication for CH correlated with worse neurodevelopmental outcomes. Conclusion: The CH group had worse neurodevelopmental outcomes and reduced height-for-age z-score. Outcomes were worse when onset of treatment was increasingly delayed.

Background: Recent studies reported that prepregnancy body mass index (BMI) and weight gain during pregnancy affect birth weight and contribute to childhood obesity. However, no such data are available in Korea.Purpose: This study gathered data on weight gain during pregnancy and its impact on birth weight and childhood obesity in Korea.Methods: We reviewed 1,753 singleton full-term babies born at CHA Bundang Medical Center in 2014–2016. We first review each maternal and baby factor based on prepregnancy BMI (underweight, normal, overweight/obese) and then divided them into low, normal, and excess gestational weight gain (GWG) groups based on the American Institute of Medicine (IOM) guidelines. We reviewed the characteristics of each group and analyzed the association between maternal GWG based on IOM guidelines and child BMI after 6 years.Results: The maternal prepregnancy BMI group showed a significant difference in birth weight and child BMI at 6 years. As the prepregnancy BMI increased, the birth weight and BMI at 6 years also increased (P<0.001). Mean birth weight and child BMI at 6 years differed significantly among the GWG groups. Furthermore, excess postpartum weight gain increased the risk of childhood overweight and obesity (odds ratio, 2.21; 95% confidence interval, 1.40–3.49).Conclusion: Excess weight gain during pregnancy should be avoided due to its short- and long-term association with childhood obesity. Owing to the high prevalence of excess GWG and childhood obesity, excess weight gain during pregnancy can have significant public health implications.

Cardiotoxicity from first-generation H1-antihistamines has been debated since the 1990s. However, large-scale studies on this topic in a general pediatric population are lacking. This study aimed to assess the association between first-generation H1-antihistamine use and cardiovascular events in a nationwide pediatric population. In this case-crossover study, the main cohort included children with cardiovascular events from the National Health Insurance Service database (2008–2012 births in Korea) until 2018. The second cohort excluded children with specific birth histories or underlying cardiovascular diseases from the main cohort. Cardiovascular events of interest included cardiac arrhythmia and ischemic heart disease. Odds ratios (ORs) of cardiovascular events were estimated using conditional logistic regression models, comparing first-generation H1-antihistamine use during 0–15 days before cardiovascular events (hazard period) with use during 45–60 and 75–90 days before events (control periods). Among the participants, 1194 (59.9%) were aged 24 months to 6 years, and 1010 (50.7%) were male. Cardiovascular event risk was increased among users of first-generation H1-antihistamines (adjusted OR [aOR], 1.201; 95% confidence interval, 1.13–1.27). Significant odds of cardiovascular events persisted within 10 and 5 days (aOR, 1.25 and 1.25). In the second cohort, the association was comparable with that in the main cohort. Our findings indicate that cardiovascular event risk is increased in children who are administered first-generation H1-antihistamines.

(1) Background: Feeding behavior habits have a pattern with a certain tendency during infancy. We aimed to identify the associations between feeding patterns in infancy and the subsequent 10-year childhood disease burden. (2) Methods: Data from 236,372 infants were obtained from the national health insurance and screening program records in South Korea. Parent-administered questionnaires during infancy provided details on the feeding type and types/frequency of complementary food for analyzing feeding patterns. The outcomes were all-cause hospitalization and the development of 15 representative childhood diseases until the age of 10 years. Anthropometric measurements obtained at 6 years of age were analyzed. To estimate outcome risks while considering multiple risk factors, we employed a Cox proportional hazard and modified Poisson regression. (3) Results: Three clusters were identified: high prevalence of breastfeeding with regular exposure to a variety of solid foods (n = 116,372, cluster 1), similar prevalence of breastfeeding and formula feeding with less exposure to solid foods (n = 108,189, cluster 2), and similar prevalence of breastfeeding and formula feeding with the least exposure to solid foods in infancy (n = 11,811, cluster 3). Compared with cluster 1, children in clusters 2 and 3 had increased risks of all-cause hospitalization (hazard ratio (HR), (95% confidence interval (CI)), 1.04 (1.03–1.06) and 1.08 (1.05–1.11), respectively). Children in clusters 2 and 3 had an increased risk of upper respiratory infection, pneumonia, and gastroenteritis, as well as neurobehavioral diseases. Overweight/obesity at the age of 6 years was associated with clusters 2 and 3. (4) Conclusions: Feeding patterns in infancy were associated with an increased risk of childhood disease burden.

Lee E, et al. Allergy Asthma Immunol Res. 2024 Sep;16(5):490-504. https://doi.org/10.4168/aair.2024.16.5.490

Background: The COVID‐19 pandemic disrupted the seasonal patterns of pediatric respiratory infections, likely due to an immunologic gap. However, the roles of weather conditions and viral interactions in age‐specific transmission, seasonality, and coinfections remain unclear. Methods: This retrospective study analyzed data from children hospitalized with respiratory tract infections between January 2012 and December 2023 at a single tertiary center in Korea. Six common respiratory viruses were identified via multiplex polymerase chain reaction (PCR). The study period was divided into prepandemic (January 2012 to January 2020), pandemic (February 2020 to November 2021), and postpandemic (December 2021 to December 2023) periods. Pandemic‐period patients ( n = 171) were excluded from comparative analyses. Virus positivity, coinfection rates, and demographic differences were assessed using chi‐square tests and t ‐tests. Time‐series analysis using seasonal autoregressive integrated moving average models (SARIMA and SARIMAX) was conducted to compare observed and predicted trends. Results: Among 12,306 hospitalized children, 86.3% were in the prepandemic period and 12.3% in the postpandemic period. Median age rose from 20.0 to 27.0 months. Rhinovirus (21.3%–43.7%) and human metapneumovirus (6.6%–9.6%) increased, while influenza declined (4.8%–2.8%). Seasonal patterns shifted, with higher positivity in summer and autumn. Observed trends diverged from SARIMAX predictions, suggesting changes not fully explained by the meteorological variables included in the model. Coinfections with three or more viruses rose (1.7%–3.0%), and virus‐negative proportions decreased (32.6%–16.7%). RSV showed three peaks in the postpandemic period, suggesting possible shifts in viral cocirculation patterns. Conclusion: Shifts in pediatric respiratory virus patterns were observed in the postpandemic period and were not fully explained by meteorological variables alone, highlighting the need for adaptive surveillance incorporating broader environmental and demographic factors.