Variation in term birthweight across European countries affects the prevalence of small for gestational age among very preterm infants.

Jennifer Zeitlin,Jan Mazela,Ludwig Gortner,Henrique Barros,Patrick Van Reempts,Aurelie Piedvache,Rolf F Maier,Anna-Karin Edstedt Bonamy,Pierre-Henri Jarreau,The Epice Research Group ,Marina Cuttini,Elizabeth S Draper

doi:10.1111/apa.13899

Abstract

This study assessed the prevalence of small for gestational age (SGA) among very preterm (VPT) infants using national and European intrauterine references. We generated country-specific and common European intrauterine growth references for 11 European countries, according to Gardosi's approach and Hadlock's foetal growth model, using national data on birthweights by sex. These references were applied to the Effective Perinatal Intensive Care in Europe (EPICE) cohort, which comprised 7766 live VPT births without severe congenital anomalies under 32 weeks of gestation in 2011-2012, to estimate the prevalence of infants with SGA birthweights, namely those below the 10th percentile. The SGA prevalence was 31.8% with country-specific references and 34.0% with common European references. The European references yielded a 10-point difference in the SGA prevalence between countries with lower term birthweights (39.9%) - Portugal, Italy and France - and higher term birthweights, namely Denmark, the Netherlands, Sweden (28.9%; p < 0.001). This was not observed with country-specific references, where the respective figures were 32.4% and 33.9% (p = 0.34), respectively. One-third of VPT infants were SGA according to intrauterine references. Common European references showed significant differences in SGA prevalence between countries with high and low-term birthweights.

Highlights

Neonatal growth references based on birthweight are not appropriate for very preterm (VPT) infants, who are more likely to have abnormal foetal growth than infants born at term
This study aimed to describe the prevalence of small for gestational age (SGA) among VPT infants using Gardosi’s methodology, overall and for key subgroups, and to evaluate the impact of using country-specific versus common European references
Our study found that about one-third of VPT infants had a birthweight that was less than the 10th percentile, and 20% were less than the 3rd percentile

Summary

Introduction

Neonatal growth references based on birthweight are not appropriate for very preterm (VPT) infants, who are more likely to have abnormal foetal growth than infants born at term. Intra-uterine growth references make it possible to avoid this bias, as they are based on estimated foetal weights calculated from ultrasound measures in normal pregnancies ending at term. Between 25% and 35% of VPT infants are Abbreviations CA, Congenital anomalies; CV, Coefficient of variation; EPICE, Effective Perinatal Intensive Care in Europe; FGR, Foetal growth restriction; GA, Gestational age; HELLP, Haemolysis, elevated liver enzymes, low platelet count; SGA, Small for gestational age; VPT, Very preterm. Classified as small for gestational age (SGA) when intrauterine curves are used, as they have a birthweight below. Key notes We assessed the prevalence of small for gestational age (SGA) among 7766 very preterm infants from 11 countries in the Effective Perinatal Intensive Care in Europe cohort. We compared European intra-uterine growth references with national references that adjusted for term birthweight in each country. Using intra-uterine curves instead of neonatal growth curves improves predictions of infant mortality and morbidity risks [5,6]

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