Prematuridade e composição corporal na infância, adolescência e idade adulta: Coortes de Nascimentos de Pelotas de 1982, 1993 e 2004

Abstract

Annually around 15 million preterm babies are born in the world. Prematurity (<37 weeks of gestational age - GA) is globally recognized as a public health problem, causing more than 1 million deaths in children under 5 years of age. The deprivation of growth and intrauterine nutrition in the last trimester of pregnancy are linked to some alterations in body composition throughout life, which may result in worse health outcomes in individuals born preterm. In this thesis, associations between gestational age (GA), especifically prematurity and weight for GA, on body composition were investigated in four stages of life, at 6, 11, 18, and 30 years in Pelotas Birth Cohorts. The evaluations at 6 and 11 years were carried out with data from the 2004 Pelotas Birth Cohort, and at 18 and 30 years with data from the 1993 and 1982 Pelotas Birth Cohorts, respectively. The body composition measures assessed by air is placement plethysmography were fat mass (FM in kg), percent FM (%FM), FM index (FMI in kg/m2 ), fat free mass (FFM in kg), percent FFM (%FFM), and FFM index (FFMI in kg/m2 ), along with BMI (in kg/m2 at 18 and 30 years and BMI z-score at 6 years). Finally, the literature was systematically reviewed with the objective of identifying studies that had evaluated body composition by indirect methods (more accurate), longitudinally, in childhood, adolescence, and adulthood. Generally, the results presented throughout the thesis point out that prematurity is associated with lower FM and FFM in childhood, inverting this relationship in late adolescence and adulthood for FM, and disappearing for FFM. In the 2004 Pelotas Birth Cohort, at 11 years of age, boys born large for GA (LGA) had higher FMI and BMI Z-scores, and girls LGA had higher FFMI than their counterparts with adequate weight for GA (AGA). At 30 years of age, men who were born with ≤33 weeks of GA had, on average, 15kg more of FM than men who were born with 37 weeks or more of GA. In addition, there seems to be a sex-dependent relationship, since significant results appear, in most cases, only for males.