Body composition of New Zealand-born term babies differs by ethnicity, gestational age and sex

T Alexander; C A Conlon; G Gamble; P R von Hurst; L van Dorp; B Ichhpuniani; R Housh; P Ke; F H Bloomfield

doi:10.1016/j.earlhumdev.2019.104924

Body composition of New Zealand-born term babies differs by ethnicity, gestational age and sex

Early Hum Dev. 2020 Jan:140:104924. doi: 10.1016/j.earlhumdev.2019.104924. Epub 2019 Nov 15.

Authors

T Alexander¹, C A Conlon², G Gamble³, P R von Hurst², L van Dorp², B Ichhpuniani², R Housh⁴, P Ke⁴, F H Bloomfield³

Affiliations

¹ Liggins Institute, University of Auckland, Auckland, New Zealand; Neonatal Unit, Kidz First, Middlemore Hospital, Auckland, New Zealand. Electronic address: tanith.alexander@middlemore.co.nz.
² School of Sport, Exercise & Nutrition, Massey University, Auckland, New Zealand.
³ Liggins Institute, University of Auckland, Auckland, New Zealand.
⁴ College of Health & Rehabilitation Sciences: Sargent College, Boston University, Boston, United States.

PMID: 31739266
DOI: 10.1016/j.earlhumdev.2019.104924

Abstract

Background: Body composition provides important information on nutrition and future metabolic risk. New Zealand has a diverse ethnic population for which there are no newborn body composition data.

Aim: To determine body composition in a cohort of New Zealand-born term babies.

Study design: Observational study.

Subjects: Healthy, term infants between 37⁺⁰ and 41⁺⁶ weeks' gestation in two hospitals in Auckland, New Zealand.

Outcome measures: Body composition by air displacement plethysmography and anthropometry measured within 5 days of birth. Parent-identified ethnicity was prioritised according to Ministry of Health criteria. Data were analysed using t-test, ANOVA with Tukey post-hoc tests, quantile regression and are mean(SD).

Results: 440 babies (54% male) were included. Pacific Island/Māori (PI/M) were heavier at birth than Asian/Middle Eastern/Latin American/African (Asian+) babies (3403(506) vs 3181(485) g, p < .05). PI/M and European (E) babies were longer with larger head and waist circumferences than Asian+ babies (all p < .05). Absolute fat mass (FM) was not different amongst ethnicities (E, 365(156), PI/M, 347(183), Asian+, 357(188) g) but PI/M babies had significantly lower FM% than Asian+ (9.8(4.3) vs 10.9(4.5) %, p < .05). Fat-free mass (FFM) was greater in PI/M (3056(400) g) than E (2952(345) g (p < .05) and both PI/M and E had greater FFM than Asian+ (2824(363) g, p < .05). Early term babies had less FFM than term and late-term babies (2732(370), 3012(352), 3173(302)g, p < .001) respectively.

Conclusions: Asian+ babies were the smallest babies with the least FFM yet had similar FM and the highest FM%, indicative of a thin, fat phenotype from birth.

Keywords: Air displacement plethysmography; Fat-free mass index; Metabolic risk; Māori; Thin-fat phenotype.