ABSTRACT
The first 1,000 days, a period that spans from conception until 2 years of age, is a critical period of life. Optimal growth and development during this sensitive period is central to neonatal health and, ultimately, health throughout the lifespan. Historically, from the 1920s to the 1950s the terms low birth weight and premature were used synonymously in literature. There is no general consensus on the definition of small for gestational age (SGA), thus several definitions exist. To measure SGA, gestational dating, precise measurements of weight and length at birth, and reference population data are key factors to consider. According to the latest Global Nutrition Report, in 2014, globally 15" of infants were born low birth weight (LBW), or 20 million births per year. The prevalence and incidence of morbidity and mortality is often estimated to understand the impact of SGA and LBW worldwide.
