Low birth weight: epidemiology, risk factors, and prevention strategies. A narrative review

Abstract

Introduction: Low birth weight, defined as a weight below 2500 grams in live newborns, is a fundamental indicator of maternal and child health and a predictor of neonatal morbidity and mortality with consequences throughout the entire life course. Objective: To comprehensively describe the current state of knowledge on low birth weight, covering its epidemiology, pathophysiological mechanisms, maternal risk factors, and strategies for detection, management, and prevention. Methods: A narrative literature review was conducted through searches in PubMed/MEDLINE, SciELO, LILACS, and Google Scholar, using the Health Sciences Descriptors (DeCS) and Medical Subject Headings (MeSH) “low birth weight infant,” “premature birth,” “fetal growth retardation,” and “risk factors,” complemented with clinical practice guidelines and technical documents from the World Health Organization. Development: Low birth weight affects 14.7% of live births worldwide and arises from two pathophysiological pathways—prematurity and intrauterine growth restriction—driven by largely modifiable maternal nutritional, metabolic, toxic, and infectious determinants. Antenatal ultrasound and Doppler surveillance, together with standardized neonatal care protocols, help mitigate its immediate and long-term complications. Conclusions: Low birth weight is a critical factor for neonatal survival and human development. Translating the accumulated scientific knowledge into scalable preventive strategies is necessary to achieve the reduction targets set by the World Health Organization.