Ethnic Differences in Neonatal Body Composition in a Multi-Ethnic Population and the Impact of Parental Factors: A Population-Based Cohort Study

Background: Neonates from low and middle income countries (LAMIC) tend to have lower birth weight compared with Western European (WE) neonates. Parental height, BMI and maternal parity, age and educational level often differ according to ethnic background, and are associated with offspring birth weight. Less is known about how these factors affect ethnic differences in neonatal body composition. Objectives: To explore differences in neonatal body composition in a multi-ethnic population, and the impact of key parental factors on these differences. Methods: A population-based cohort study of pregnant mothers, fathers and their offspring, living in Oslo, Norway. Gender- and gestational-specific z-scores were calculated for several anthropometric measurements, with the neonates of WE ethnic origin as reference. Mean z-scores for neonates with LAMIC origin, and their parents, are presented as outcome variables. Results: 537 singleton, term neonates and their parents were included. All anthropometric measurements were smaller in neonates with LAMIC origin. Abdominal circumference and ponderal index differed the most from WE (mean z-score: -0.57 (95% CI: -0.69 to -0.44) and -0.54 (-0.66 to -0.44), and remained so after adjusting for parental size. Head circumference and skin folds differed less, and length the least (-0.21 (-0.35 to -0.07)). These measures became comparable to WEs when adjusted for parental factors. Conclusions: LAMIC origin neonates were relatively thin-fat'', as indicated by reduced AC and ponderal index and relatively preserved length and skin folds, compared with neonates with WE origin. This phenotype may predispose to type 2 diabetes.