Weight gain speed and z-score behavior in large prematures for gestational age

Objective: to investigate the speed of weight gain (WG) and the z-score (E-z) of weight in premature neonates large for gestational age (LGA) during four weeks of hospitalization. Methods: a retrospective longitudinal study with premature neonates in a neonatal intensive care unit at a university hospital. Data were obtained from January 2017 to December 2018; 115 babies with gestational age (GA) ≥ 27 and < 37 weeks, non-twin, AGA or LGA were included. The WG (g/kg/day) was obtained from the nadir weight and the E-z was calculated online based on the Intergrowth-21st curves. Repeated-measures ANOVA and multiple linear regression were used to assess the association between WP and E-z and explanatory variables; p < 5 %. Results: mean GA was 32.5 weeks, birth weight was 1910 g and weight loss was 5 % at 7 days. WG was lower in LGA babies, with GI between 32 and 37 weeks (LGA, 9.2 ± 5.6 g/kg/day vs AGA, 13.9 ± 6.0 g/kg/day). The change in WG was explained by protein supply in AGA (B = 2.5 g/kg/day; 95 % CI, 0.7 to 4.3; and β = 0.543) and by GA in LGA (B = -0.05 g/kg/day; 95 % CI, -0.09 to -0.02; and β = -0.574). In the 4th week of hospitalization, weight E-z decreased similarly for LGAs and AGAs, and this variation was explained by growth. Conclusions: premature LGAs had lower WG compared to AGAs during the neonatal period. The linear and brain growth explained the variation in weight E-z among these preterms.