A comprehensive narrative review of critical windows of vulnerability in brain development and environmental exposures: timing matters

This narrative review synthesises recent evidence on how climatic and environmental exposures shape neurodevelopment across sensitive windows. A search of Embase, PubMed, Scopus, and Web of Science (January 2020–April 2026) identified 46 studies spanning epidemiology, clinical outcomes, mechanisms and neuroimaging. Climatic stressors (temperature extremes, rainfall shocks, superstorms, El Niño–Southern Oscillation) and pollutants (PM₂.₅/NO₂/O₃/PAHs; Pb/Hg/Cd/As/Mn; organophosphates/pyrethroids; phthalates/bisphenols/PFAS) were consistently associated with increased risk of adverse neurodevelopmental outcomes across critical developmental windows, including language, attention, executive and motor function, emotion regulation and mental health. Neuroimaging studies reported changes in white matter maturation, hippocampal and amygdala development, basal ganglia and cortical morphology and large-scale functional connectivity. Converging mechanisms - including oxidative stress, neuroinflammation, endocrine and placental dysfunction, vascular injury and immune activation - provide biological plausibility; epigenetic modifications may act as shared integrators or independent pathways influencing long-term outcomes. Vulnerability peaked from periconception through early postnatal life, with infancy–toddlerhood and adolescence as additional sensitive phases. Socioeconomic disadvantage, co-exposures and contextual factors (urban heat islands; mining, agricultural and flood-prone areas) amplified risk, while cash transfers, breastfeeding and adaptive practices were protective. Environmental and climatic exposures are modifiable determinants of child brain health. Environmental factors should be considered - at least - within routine maternal and childcare through brief screening of potentially modifiable exposures. Schools and communities also play a role in awareness and adaptive responses. Coordinated, context-sensitive research using harmonised exposome-based models is needed. Protecting the developing brain from environmental and climatic threats is a scientific and ethical imperative aligned with the Sustainable Development Goals.