Neonatal hypoglycaemia and body proportionality in small for gestational age newborns: a retrospective cohort study

Small for gestational age (SGA) newborns are at risk of developing neonatal hypoglycaemia. SGA newborns comprise a heterogeneous group including both constitutionally small and pathologically growth restricted newborns. The process of fetal growth restriction may result in brain sparing at the expense of the rest of the body, resulting in disproportionally small newborns. The aim of this study was to discover whether body proportionality influences the risk of developing neonatal hypoglycaemia in SGA newborns. A retrospective cohort study was performed in 402 newborns who were SGA without additional risk factors for hypoglycaemia. Body proportionality was classified in two ways: (1) using symmetric (sSGA) or asymmetric (aSGA), defined as head circumference (HC) below or above the 10th percentile, respectively; (2) using cephalization index (HC/birth weight), standardized for gestational age. Hypoglycaemia was observed in 50% of aSGA and 40.9% of sSGA newborns (P-value 0.12). Standardized CI in newborns with hypoglycaemia was higher compared to newborns without hypoglycaemia (median 1.27 (1.21-1.35) versus 1.24 (1.20-1.29); (P 0.002)). Multivariate logistic regression analyses showed both CI and standardized CI to be associated with the occurrence of hypoglycaemia (OR 1.48 (1.24-1.77) and OR 1.44 (1.13-1.83), respectively). The majority of hypoglycaemic events (96.1%) occurred in the first 6 h after birth.   Conclusion: Body proportionality might be of influence, depending on the classification used. Larger prospective studies with a clear consensus definition of body proportionality are needed. What is Known: • Neonatal hypoglycaemia is an important complication in newborns. • Small for gestational age (SGA) newborns are more vulnerable to hypoglycaemia. What is New: • Higher incidence of hypoglycaemia was not observed in asymmetric SGA compared to symmetric SGA, but standardized cephalization index was associated with increased likelihood of hypoglycaemia. • Consensus-based definitions of body proportionality in newborns are needed.