ObjectiveTo evaluate whether in preterm neonates parenteral nutrition use in the first 7 postnatal days, compared with no parenteral nutrition use, is associated with differences in survival and other important morbidities. Randomised trials in critically ill older children show that harms, such as nosocomial infection, outweigh benefits of early parenteral nutrition administration; there is a paucity of similar data in neonates.DesignRetrospective cohort study using propensity matching including 35 maternal, infant and organisational factors to minimise bias and confounding.SettingNational, population-level clinical data obtained for all National Health Service neonatal units in England and Wales.PatientsPreterm neonates born between 30+0 and 32+6 weeks+days.InterventionsThe exposure was parenteral nutrition administered in the first 7 days of postnatal life; the comparator was no parenteral nutrition.Main outcome measuresThe primary outcome was survival to discharge from neonatal care. Secondary outcomes comprised the neonatal core outcome set.Results16 292 neonates were compared in propensity score matched analyses. Compared with matched neonates not given parenteral nutrition in the first postnatal week, neonates who received parenteral nutrition had higher survival at discharge (absolute rate increase 0.91%; 95% CI 0.53% to 1.30%), but higher rates of necrotising enterocolitis (absolute rate increase 4.6%), bronchopulmonary dysplasia (absolute rate increase 3.9%), late-onset sepsis (absolute rate increase 1.5%) and need for surgical procedures (absolute rate increase 0.92%).ConclusionsIn neonates born between 30+0 and 32+6 weeks’ gestation, those given parenteral nutrition in the first postnatal week had a higher rate of survival but higher rates of important neonatal morbidities. Clinician equipoise in this area should be resolved by prospective randomised trials.Trial registration numberNCT03767634.