Cohort study showed that growth rate increment has not been enough to prevent growth retardation of preterm infants and raised concerns about unbalanced growth

Aim: We describe the postnatal weight gain, linear and head growth trends of surviving preterm infants from 2005 to 2017. Methods: Multicentre cohort study, including surviving preterm infants <32 weeks (n = 21 084), from the Spanish Neonatal Network database, without major congenital malformations who were less than 50 weeks postmenstrual age at discharge. Outcomes were weight gain (g/kg/day), linear and head growth (cm/week) and changes in weight, length and head circumference z-scores from birth to discharge. The study period was divided into 2005-8, 2009-11, 2012-14 and 2015-17. Results: Weight gain, linear growth and head growth were slightly higher in 2015-2017 than in 2005-2008: 12.2 +/- 2.6 to 13.1 +/- 2.5 g/kg/day, 0.98 +/- 0.6 to 1.03 +/- 0.6 cm/week and 0.76 +/- 0.2 to 0.77 +/- 0.3 cm/week, respectively. It was associated with a decreased fall in weigh, length and head circumference z-scores from birth to discharge (-1.32 +/- 0.9 to -1.01 +/- 0.84, -1.38 +/- 1.2 to -1.18 +/- 1.2 and -0.41 +/- 1.2 to -0.33 +/- 1.3, respectively). Conclusion: Postnatal growth restriction remained a common complication of prematurity despite some increment over the last years. Growth disproportionality seemed to be worsening as weight gain was increased more than linear growth.