Infant body mass index peak and early childhood cardio-metabolic risk markers in a multi-ethnic Asian birth cohort

Abstract

Background: : Infant body mass index (BMI) peak has received much interest recently as a potential predictor of future obesity and metabolic risk. No studies, however, have examined infant BMI peak in Asian populations, in whom the risk of metabolic disease is higher.

Methods: : We utilized data among 1020 infants from a mother-offspring cohort, who were Singapore citizens or permanent residents of Chinese, Malay or Indian ethnicity with homogeneous parental ethnic backgrounds, and did not receive chemotherapy, psychotropic drugs or have diabetes mellitus. Ethnicity was self-reported at recruitment and later confirmed using genotype analysis. Subject-specific BMI curves were fitted to infant BMI data using natural cubic splines with random coefficients to account for repeated measures in each child. We estimated characteristics of the child's BMI peak [age and magnitude at peak, average pre-peak velocity (aPPV)]. Systolic (SBP) and diastolic blood pressure (DBP), BMI, sum of skinfolds (SSF) and fat-mass index (FMI) were measured during a follow-up visit at age 48 months. Weighted multivariable linear regression was used to assess the predictors (maternal BMI, gestational weight gain, ethnicity, infant sex, gestational age, birthweight-for-gestational age and breastfeeding duration) of infant BMI peak and its associations with outcomes at 48 months. Comparisons between ethnicities were tested using Bonferroni post-hoc correction.

Results: : Of 1020 infants, 80.5% were followed up at the 48-month visit. Mean (SD) BMI, SSF and FMI at 48 months were 15.6 (1.8) kg/m 2 , 16.5 (5.3) mm and 3.8 (1.3) kg/m 2 , respectively. Mean (SD) age at peak BMI was 6.0 (1.6) months, with a magnitude of 17.2 (1.4) kg/m 2 and pre-peak velocity of 0.7 (0.3) kg/m 2 /month. Compared with Chinese infants, the peak occurred later in Malay {B [95% confidence interval (CI): 0.64 mo (0.36, 0.92)]} and Indian infants [1.11 mo (0.76, 1.46)] and was lower in magnitude in Indian infants [-0.45 kg/m 2 (-0.69, -0.20)]. Adjusting for maternal education, BMI, gestational weight gain, ethnicity, infant sex, gestational age, birthweight-for-gestational-age and breastfeeding duration, higher peak and aPPV were associated with greater BMI, SSF and FMI at 48 months. Age at peak was positively associated with BMI at 48 months [0.15 units (0.09, 0.22)], whereas peak magnitude was associated with SBP [0.17 units (0.05, 0.30)] and DBP at 48 months [0.10 units (0.01, 0.22)]. Older age and higher magnitude at peak were associated with increased risk of overweight at 48 months [Relative Risk (95% CI): 1.35 (1.12-1.62) for age; 1.89 (1.60-2.24) for magnitude]. The associations of BMI peak with BMI and SSF at 48 months were stronger in Malay and Indian children than in Chinese children.

Conclusions: : Ethnic-specific differences in BMI peak characteristics, and associations of BMI peak with early childhood cardio-metabolic markers, suggest an important impact of early BMI development on later metabolic outcomes in Asian populations.

Trial registration: ClinicalTrials.gov NCT01174875.

Keywords: adiposity; blood pressure; body composition; cardio-metabolic risk markers; cohort study; infant growth.

Figure 1.

GUSTO recruitment flow chart and eventual study sample.

Figure 2.

Infant BMI trajectory in the first 18 months according to (a) sex, (b) ethnicity, (c) size at birth and (d) exclusive breastfeeding duration. AGA, appropriate-for-gestational-age; SGA, small-for-gestational-age; LGA, large-for-gestational-age; Exc BF, exclusive breastfeeding. Error bars represent ±1 SE.

Figure 3.

(a) Association of infant BMI peak characteristics with cardio-metabolic markers at 48 months. Data symbols represent regression coefficient estimates, error bars represent 95% confidence intervals. Black diamond = age at peak; black triangle = magnitude at peak; black square = average pre-peak velocity. Regression models with BMI, SSF and FMI as outcomes were adjusted for maternal education, ppBMI, gestational weight gain, ethnicity, infant sex, gestational age, birthweight-for-gestational-age, breastfeeding duration and actual age at measurement. Regression models with SBP and DBP as outcomes were adjusted for the same covariates, with the addition of maternal blood pressure. Regressions of age or magnitude at peak with each cardio-metabolic marker included both age and magnitude at peak in the same model. * p < 0.05; ** p < 0.01. (b) Relative risk and 95% confidence interval of overweight and pre-hypertension at 48 months according to infant BMI peak characteristics. Data symbols represent relative risk estimates, error bars represent 95% confidence intervals. Black diamond = age at peak; black triangle = magnitude at peak; black square = average pre-peak velocity. Regression models with overweight as an outcome were adjusted for maternal education, ppBMI, gestational weight gain, ethnicity, gestational age, birthweight-for-gestational-age, breastfeeding duration and actual age at measurement. Regression models with pre-hypertension as an outcome were adjusted for the same covariates, with the addition of maternal blood pressure. Regressions of age or magnitude at peak with overweight and pre-hypertension included both age and magnitude at peak in the same model. * p < 0.05; ** p < 0.01.