Aim: To assess the growth trajectory of preterm small-for-gestational-age (SGA) neonates compared to preterm non-small-for-gestational age neonates in the neonatal intensive care unit and special care nursery.
Methods: We conducted a retrospective cohort study at a large tertiary hospital in Victoria, Australia, examining neonates ≤34 weeks' gestation admitted to the neonatal intensive care unit or special care nursery between 2013 and 2017. We categorized neonates according to their birth weight centile: <10th centile (small-for-gestational age) and ≥10th centile (non-small-for-gestational age). Growth trajectory was tracked based on serial weights obtained in the neonatal intensive care unit and special care nursery, using z-scores derived from Fenton preterm growth charts. Our primary outcome was the change in weight z-score from birth to discharge from neonatal intensive care unit or special care nursery.
Results: Of the 910 babies included, 88 were small-for-gestational age and 822 were appropriate-for gestational age. Both groups had a reduction in their weight z-score; however, SGA babies had a significantly smaller reduction (-0.62 SD compared to -0.85 SD, p < .0001). Small-for-gestational-age neonates were four times more likely to experience an increase in their weight z-score across their admission compared to neonates who were not small-for-gestational age (OR 4.04, 95% CI 2.23-7.48, p < .0001). Small-for-gestational-age neonates had an increased median length of stay, increased incidence of necrotizing enterocolitis but a reduced incidence of intraventricular hemorrhage.
Conclusions: Preterm SGA babies experience a smaller reduction in their weight trajectory compared to their appropriately grown counterparts in the neonatal intensive care unit or special care nursery.
Keywords: Growth trajectory; fetal growth restriction; intra-uterine growth restriction; neonatal; weight.