Evaluation of the INTERGROWTH-21st project newborn standard for neonatal phenotypes and neonatal morbidity and mortality

Introduction The use of local references or standard for neonatal studies still requires their validation through indicators of morbidity and mortality. Objective: evaluate the performance of the INTERGROWTH-21st Project (IG-21) standard and a commonly used Argentinian reference (Urquia) by examining the differences in the frequency of growth phenotypes, and the associated neonatal morbidity and mortality. Methods: Retrospective cohort study of all singleton live-births from Sarda Maternity Hospital (Buenos Aires, Argentina) between 33 and 42 gestational age, using information obtained from a Perinatal Surveillance System (Agustina) dataset between 1996-2001 (n = 25948). Phenotypes small- and large-for-gestational age, stunting and waisting and a composite of neonatal morbidity/mortality (CNMM) were contrasted between the IG-21 standard and Urquia reference. Results: the Urquia 3rd centile value was lower than IG-21 before 37 weeks, but then it surpassed IG-21 until term. Among Sarda , 2.3%, 5.9% and 8.9 were 97th centile, respectively, under the IG-21 standard, while 3.7%, 10.1% and 8.4% were 97th centile, respectively, under the Urquia reference. Stunting and waisting were 16.1% and 0.9%, respectively under IG-21. The IG-21 detection rates of CNMM showed that 28.5%, 19.6% and 8.5% occurred among weight97th centile, respectively, while 21.8%, 14.2% and 8.0% occurred among 97th centile under the Urquia criteria. Newborn weight 97th centile under IG-21 showed higher neonatal CNMM risk compared with Urquia reference. Conclusions: The IG-21 standard identified a higher risk of neonatal morbidity and mortality than the Urquia reference.