Temporal trends of birthweight are not driving trends of atopic dermatitis prevalence in United States children

Population-based risk-factors for the rising prevalence of childhood atopic dermatitis (AD) in the United States are not well elucidated. We hypothesized that trends of birthweight over the past 2 decades contributed to the increasing prevalence of childhood AD in the United States. We sought to determine whether trends of birthweight were associated with trends of childhood AD prevalence over time in the US. Data were analyzed from the 1997-2018 National Health Interview Survey (N = 238,767 children). The prevalence [95% confidence interval] of childhood AD increased from 1997 (7.9% [7.4-8.5%]) to 2018 (12.6% [11.6-13.5%]). Whereas, mean [95% confidence interval] birthweight decreased from 1997 (3.35 kg [3.34-3.37 kg]) to 2018 (3.30 kg [3.28-3.31 kg]). A 1 kg increase in birthweight was associated with a slightly increased odds of AD (adjusted odds ratio [95% confidence interval] 1.039 [1.009-1.070]). However, there were no significant interactions between low or high birthweight and year as predictors of childhood AD prevalence overall or in any age group. In conclusion, there is a slight association between greater birthweights and AD prevalence. However, temporal trends of birthweight do not account for trends of childhood AD prevalence in the United States.