Differences When Classifying Small for Gestational Age Preterm Infants According to the Growth Chart Applied

Abstract

Objective Consensus around the ideal chart to classify preterm babies is scant. It is particularly relevant in small for gestational age (SGA) infants due to its clinical and therapeutic implications. The aim of the study was to compare Olsen, Intergrowth-21st, and Fenton growth charts, regarding the classification at birth and incidence of SGA preterm infants. Study Design Retrospective study of 529 preterm infants ≤ 32 weeks of gestational age. Birth weight Z-score was calculated applying the three growth charts and ponderal index (PI) was also estimated. Incidence of SGA (birth weight < 10th percentile) and clinical outcome were compared according to the chart used. Results Incidence of SGA was significantly higher (p < 0.001) with Olsen (101 cases, 19.1%) compared with Intergrowth-21st (75 cases, 14.2%) and Fenton (53 cases, 10%). Differences were also found with PI of SGA preterm infants, as those infants classified by Olsen were mostly symmetric (PI > 10th percentile), while Fenton and Intergrowth-21st identified less symmetric SGA infants. Kappa concordance between Intergrowth-21st and Fenton was 0.805, Intergrowth-21st versus Olsen 0.824, and Fenton versus Olsen 0.641. No differences were observed on neonatal morbidities or mortality. Conclusion Significant differences were detected when classifying very preterm infants at birth according to the growth chart, mainly among symmetric SGA. Concordance between Fenton and Olsen was poor, but Intergrowth-21st showed high concordance with Fenton and Olsen. However, further research is needed to select the ideal chart. Variability in the population selected to create the curves and the accuracy dating the pregnancy are factors that may have explained differences. Key Points

Comparison of Intergrowth-21st and Fenton growth standards to evaluate and predict the postnatal growth in eastern Chinese preterm infants

“…To our best knowledge, many studies abroad had explored the application of IG-21 curves in different populations. The studies by Anne et al ( 9 ), Reddy et al ( 15 ), and Estañ-Capell et al ( 16 ) provided the data of the application of IG-21 growth charts in early preterm birth (<32 weeks); González García et al ( 17 , 18 ) and Yazici et al ( 19 ) focused on very low birth weight infants (<1,500 g). Most research studies were limited to specific high-risk populations and overlooked the middle and late preterm infants, which occupied a large majority of preterm infants.…”

Intrauterine growth restriction, prematurity, and low birth weight: risk phenotypes of neonatal death, Rio de Janeiro State, Brazil

“…In the study of the Child Health Epidemiology Reference Group SGA - Preterm Birth Working Group, the prevalence of the low birth weight, preterm and SGA phenotype was 0.7% in Latin America, 1.6% in Africa, and 2.3% in Asia 27 . Regarding the methodological choices, the factors include different diagnostic approaches to gestational age 28 , different curves to assess the adequacy of weight for gestational age 22 , 29 , 30 , the type of basis of the study - population or hospital - the inclusion and exclusion criteria of newborns, especially at risk, such as twins and those with congenital malformations, who usually have higher frequencies of low weight, prematurity, and fetal growth restriction 31 , 32 , 33 . Notably, in Brazil, most deliveries occur in hospitals, which would be less relevant for national studies 15 .…”

“…After classification, live births were described according to maternal characteristics. Sociodemographic variables included age group (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) and ≥ 35 years old); skin color (white, black and brown), and schooling (0-3; 4-7 and ≥ 8 years of study). Parity was evaluated according to the number of previous deliveries (zero: primiparous and ≥ 1: multiparous).…”

Restrição do crescimento intrauterino, prematuridade e baixo peso ao nascer: fenótipos de risco de morte neonatal, Estado do Rio de Janeiro, Brasil

“…No estudo do Child Health Epidemiology Reference Group SGA -Preterm Birth Working Group, a prevalência do fenótipo baixo peso ao nascer, pré-termo e PIG foi de 0,7% na América Latina, 1,6% na África e 2,3% na Ásia 27 . Quanto às escolhas metodológicas, os fatores abrangem diferentes abordagens diagnósticas da idade gestacional 28 , diferentes curvas para avaliar adequação do peso para idade gestacional 22,29,30 , tipo de base do estudo -populacional ou hospitalar -, critérios de inclusão e exclusão dos recém-nascidos (principalmente de risco, como gemelares e aqueles portadores de malformações congênitas, que costumam apresentar mais frequentemente baixo peso, prematuridade e restrição do crescimento fetal) 31,32,33 . Deve ser lembrado que, no Brasil, a grande maioria dos partos ocorre em hospitais; portanto, este fator pesaria menos para estudos nacionais 15 .…”