Recém-nascidos prematuros grandes para a idade gestacional: ganho de peso e comportamento do escore-z de peso durante a internação em Unidade de Terapia Intensiva Neonatal

Abstract

Introduction: Premature birth requires multiple adaptations to the extrauterine environment. In particular, the abrupt interruption of the transfer of nutrients interferes with the growth rate of babies and requires surveillance of their nutritional status. The nutritional status of preterm infants at birth can be classified according to weight and gestational age into: small for gestational age (SGA), adequate for gestational age (AGA) or large for gestational age (LGA). In the neonatal period, the assessment of nutritional status requires an association of measures and parameters, for example the behavior of the z score (Ez) of growth must be analyzed with the speed of weight gain (WG), since these babies rarely reach the rate of intrauterine growth. The extremes of nutritional status at birth, SGA or LGA, are associated with a higher risk of neonatal death and disease in later life. Premature LGA in the face of accelerated neonatal WG are more likely to increase adiposity and to develop cardiometabolic and neurological diseases when compared to AGA. However, the number of studies on the growth of premature LGA in the neonatal period is limited, as well as its long term consequence. The reference for the adequate WG of premature infants is the intrauterine rate, however the effort to maintain this rate in the extrauterine environment is an arbitrary conduct, especially for LGA. Objective: To investigate the speed of WG and the weight Ez in premature neonates LGA, during four weeks of hospitalization. Methods: Retrospective longitudinal study with premature 12 neonates from a neonatal intensive care unit from a university hospital. Data were obtained from January 2017 to December 2018. 115 babies with gestational age (GA) ≥ 27 and <37 weeks, not twin, AGA or LGA were included. The WG (g/kg/day) was obtained from the nadir weight and the Ez was calculated online based on the Intergrowth-21st curves. Repeated measurements ANOVA and multiple linear regression were used to assess the association between WG and Ez and explanatory variables, p <5%. Results: The mean GA was 32,5 weeks, birth weight 1910g and weight loss was 5% at 7 days. The WG was lower in LGA babies, with GA between 32 and 37 weeks (LGA 9.2 ± 5.6g/kg/day vs AGA 13.9 ± 6.0g/kg/day). The change in WG was explained by the protein supply in AGA (B 2.5g/kg/day, 95% CI 0.7; 4.3 and β 0.543) and by GA in LGA (B -0.05g/kg/day, 95% CI -0.09; -0.02 and β -0.574). In the 4th week of hospitalization, the weight E-z reduced similarly for LGA and AGA and this variation was explained by the increase in height Ez and head circumference. Discussion: The WG rate of LGA babies was lower than that of premature AGA in the neonatal period. The GA and the protein supply explained, significantly, the variation in the speed of WG in the premature neonates LGA and AGA, respectively. The difference in weight E-z was similar between LGA and AGA and indicated the babies' growth. Conclusions: Moderately premature LGA neonates showed a lower WG rate than premature AGA ones. During hospitalization, the weight Ez was obtained from the weight nadir and its variation was explained by the linear and brain growth of premature infants.