PRENATAL AND POSTNATAL FACTORS CONTRIBUTING TO NEURODEVELOPMENTAL DELAY IN YOUNG CHILDREN: A COMPREHENSIVE REVIEW OF MECHANISMS AND EVIDENCE

Neurodevelopmental delay in early childhood represents a significant global health burden with lifelong implications for individual potential and societal human capital. The etiology of these delays is multifactorial, arising from complex interactions between genetic susceptibility and environmental exposures across prenatal and postnatal developmental windows. This comprehensive review synthesizes current evidence from epidemiological cohorts, neurobiological studies, and genetic investigations to examine the relative contributions and mechanistic pathways of prenatal and postnatal risk factors. Prenatal determinants examined include maternal metabolic conditions (obesity, diabetes, hypertension), maternal mental health disorders (stress, anxiety, depression), nutritional deficiencies (iron, iodine, folate), environmental toxicants, and genetic variants. Postnatal factors analyzed encompass maternal stress during the first year of life, preterm birth complications, low birth weight, nutritional insufficiency, infectious and inflammatory exposures, and socioeconomic determinants. Emerging evidence demonstrates that while prenatal factors establish foundational neuroarchitecture through fetal programming mechanisms, postnatal environmental influences may exert stronger direct effects on developmental trajectories and present greater opportunities for resilience-building interventions. Critical gene-environment interactions modify individual susceptibility, with pathogenic variants in glutamatergic, dopaminergic, and synaptic pathways conferring differential vulnerability to environmental stressors. The pooled prevalence of developmental delay in low- and middle-income countries reaches 18.83%, with maternal education and low birth weight identified as predominant determinants. This review advocates for integrated life-course perspectives in clinical practice and public health policy, emphasizing that targeted postnatal interventions can significantly modify developmental outcomes irrespective of prenatal adversity.