Low birth weight and obesity: causal or casual casual association?

ObjectiveTo present the conceptual foundations that explain how events occurring during intrauterine life may influence body development, emphasizing the interrelation between low birth weight and risk of obesity throughout life.Data sourcesGoogle Scholar, Library Scientific Electronic Online (SciELO), EBSCO, Scopus, and PubMed were the databases. “Catch-up growth”, “life course health”, “disease”, “child”, “development”, “early life”, “perinatal programming”, “epigenetics”, “breastfeeding”, “small baby syndrome”, “phenotype”, “micronutrients”, “maternal nutrition”, “obesity”, and “adolescence” were isolated or associated keywords for locating reviews and epidemiological, intervention and experimental studies published between 1934 and 2014, with complete texts in Portuguese and English. Duplicate articles, editorials and reviews were excluded, as well as approaches of diseases different from obesity.Data synthesisWithin 47 selected articles among 538 eligible ones, the thrifty phenotype hypothesis, the epigenetic mechanisms and the development plasticity were identified as fundamental factors to explain the mechanisms involved in health and disease throughout life. They admit the possibility that both cardiometabolic events and obesity originate from intrauterine nutritional deficiency, which, associated with a food supply that is excessive to the metabolic needs of the organism in early life stages, causes endocrine changes. However, there may be phenotypic reprogramming for low birth weight newborns from adequate nutritional supply, thus overcoming a restrictive intrauterine environment. Therefore, catch-up growth may indicate recovery from intrauterine constraint, which is associated with short-term benefits or harms in adulthood.ConclusionsDepending on the nutritional adequacy in the first years of life, developmental plasticity may lead to phenotype reprogramming and reduce the risk of obesity.

ResumoObjetivoApresentar as bases conceituais que explicam como eventos na vida intrauterina podem influenciar o desenvolvimento corporal e enfatizar a interrelação entre baixo peso ao nascer e risco de obesidade ao longo da vida.Fontes de dadosGoogle Scholar, Scientific Electronic Libraty Online (SciELO), EBSCO, Scopus e PubMed foram as bases de dados. “Catch-up growth”, “lifecourse health”, “disease”, “child”, “development”, “early life”, “perinatal programming”, “epigenetics”, “breastfeeding”, “small baby syndrome”, “phenotype”, “micronutrients”, “maternal nutrition”, “obesity” e “adolescence” foram descritores isolados ou associados para localizar revisões, estudos epidemiológicos, de intervenção ou experimentais publicados entre 1934 e 2014, com textos integrais, em português e inglês. Excluíram-se duplicidades, editoriais, resenhas e abordagens de doença diferente da obesidade.Síntese dos dadosNos 47 artigos selecionados dentre 538 elegíveis, identificaram-se as hipóteses do fenótipo poupador, dos mecanismos epigenéticos e da plasticidade do desenvolvimento como fundamentais para explicar mecanismos envolvidos na saúde e nas doenças durante a vida. Elas admitem a possibilidade de eventos cardiometabólicos e obesidade terem origem em deficiência intraútero de nutrientes que, associados a suprimento alimentar excessivo às necessidades metabólicas nas fases precoces da vida, provoca alterações endócrinas. Todavia pode haver reprogramação fenotípica que supere ambiente restritivo intrauterino para nascidos com baixo peso a partir de oferta nutricional adequada. Assim, o catch-up growth indicaria recuperação da restrição intrauterina e se associaria a benefícios em curto prazo ou prejuízos no adulto.ConclusõesNa dependência de adequação nutricional nos primeiros anos de vida, a plasticidade do desenvolvimento pode levar à reprogramação fenotípica e reduzir o risco de obesidade.