Which growth standards should be used to identify large- and small-for-gestational age infants of mothers with type 1 diabetes? A pre-specified analysis of the CONCEPTT trial

Abstract

BackgroundOffspring of women with type 1 diabetes are at increased risk of accelerated fetal growth which is associated with perinatal morbidity. Growth standards are used to identify large- or small- for gestational age (LGA, SGA) infants. Our aim was to examine which growth standards identify infants at risk of perinatal complications during the Continuous Glucose Monitoring in Type 1 Diabetes Pregnancy Trial (CONCEPTT).MethodsThis was a pre-specified analysis of CONCEPTT involving 225 pregnant women from 31 international centres. Infants were weighed immediately at birth and GROW, INTERGROWTH and WHO centiles calculated. Unadjusted logistic regression identified the associations between different growth standards and perinatal outcomes including preterm delivery, Caesarean delivery, neonatal hypoglycaemia, hyperbilirubinaemia, respiratory distress, neonatal intensive care unit (NICU) admission and a composite neonatal outcome. ResultsAccelerated fetal growth was common, with mean birthweight percentiles of 82.1, 85.7 and 63.9 and LGA rates of 62%, 67% and 30% using GROW, INTERGROWTH and WHO standards respectively. Corresponding rates of SGA were 2.2%, 1.3% and 8.9% respectively. All standards were associated with some but not all perinatal outcomes studied. Infants born >97.7th centile using GROW or INTERGROWTH standards were at highest risk of complications. Conclusions WHO standards underestimated birthweight centile. GROW and INTERGROWTH standards identified similar numbers of infants as LGA and SGA with GROW showing stronger associations with neonatal hypoglycaemia, hyperbilirubinaemia and NICU admission. Infants with suspected birthweight >97.7th centile using GROW or INTERGROWTH standards may require extra surveillance. Definitions of LGA and SGA should be re-evaluated in diabetic pregnancy. Trial registration: This trial is registered with ClinicalTrials.gov. number NCT01788527.