Early-life exposure to non-optimal temperature and emotional and behavioral problems in preschool children

The effects of early-life exposure to extreme temperatures on adverse neurodevelopmental outcomes have been increasingly investigated. However, less attention has been given to emotional and behavioral problems (EBPs). This study aimed to examine the association between early-life exposure to non-optimal temperature and EBPs among preschool children aged 2 - 6 years.

We conducted a cross-sectional study among over 4000 preschool children in Guangzhou, China. EBPs were assessed using the parent-reported Strengths and Difficulties Questionnaire (SDQ). Residential daily ambient temperature during early-life period (from conception to the date of the SDQ assessment) were assessed. Heatwave and cold spell days were defined as extreme high- and low-temperature events, respectively, lasting for at least two consecutive days. Gaussian generalized linear models with an identity link were applied to estimate the associations between non-optimal temperature and SDQ scores, adjusting for relevant confounders. Stratified analyses were conducted to identify vulnerable populations. Distributed lag nonlinear models (DLNMs) were applied to explore potential sensitive windows across period spanning pregnancy through 2 years of age.

The exposures to cooler temperature (<5th percentile, 23.79 °C) and warmer temperature (>95th percentile, 24.36 °C) were associated with a 0.357 (95% CI: 0.058, 0.656) and 0.487 (95% CI: 0.164, 0.810) higher total difficulties scores compared with the median temperature (24.09 °C) in preschool children. The significant associations were also observed across other SDQ domains and were more pronounced among children from low-income households. Potential sensitive windows for associations of heatwave and cold spell exposure with SDQ scores were identified primarily during the first two postnatal years.

Early-life exposures to non-optimal temperature were associated with increased risks of EBPs in preschool children. These findings underscore the importance of mitigating the health impacts of early-life exposure to non-optimal temperatures and developing targeted protective strategies for children from low-income households.