Abstract
Background Childhood obesity, with overweight defined as BMI z-score >2 based on WHO standards, is a growing problem in Singapore. The proportion of overweight children aged 6–18 years in Singapore has increased from 11% in 2013 to 13% in 2017. This prevalence persists into childhood as 70% of children who were overweight when 7 years old remained overweight at 11 years of age. Rapid weight gain during infancy is an established risk factor for later obesity and excess body weight tracks from infancy into childhood and adulthood. However, little is known about the growth trajectories of infants in Singapore.
Objectives The objective of this study was to examine the longitudinal growth trajectories of infants in Singapore by tracking weight gain and Body Mass Index (BMI) (both absolute and BMI z-scores) in the first 18 months of life. Additionally, maternal and child predictors of infant weight and BMI were examined. Maternal predictors include number of months of breastfeeding, maternal age, and maternal education level while infant predictors include ethnicity and gender.
Methods Retrospective data on infants attending a government-subsidised primary care clinic between July 2019 to August 2020 was collected. Maternal characteristics (maternal age at birth and maternal education level at the child’s 18-month visit) and infant characteristics (birth weight, birth height, infant gender and infant ethnicity) were recorded from electronic medical records. Weight and BMI were measured at birth, 1, 3, 6, 9, 12 and 18 months. The type of feeding (breastfeeding or formula feeding or soft diet or a mix of any of the 3) was reported at each visit. Mixed Model Repeated Measures analysis was performed to compare weight and BMI within each gender, ethnicity and number of months of breastfeeding.
Results 7125 infants attended the clinic during the study period. 50.5% of the participants were male. The majority of infants were Chinese at 68.7%, 22.8% were Malay and 5.1% were Indian. We observed a peak in BMI at 6 months of age, with a mean of 17.5 kg/m2. BMI then declined thereafter to 16.9 kg/m2 at 12 months. We identified gender and ethnic differences in weight and BMI trajectories. Males had a higher mean weight and BMI than females across all time points. Chinese infants generally had a higher mean weight and BMI as compared to Malay and Indian infants. Indian infants exhibited the lowest BMI across all time points. With regards to feeding, 86.8% of the children were breastfed at 1 month of age and the prevalence declined to 54.8% by 6 months. Breastfeeding duration was identified as an important predictor of weight and BMI as a longer duration of breastfeeding was associated with a lower weight and BMI. Longer duration of breastfeeding was associated with a lower weight and BMI even when compared to those within the same gender and race.
Conclusions This study shows that gender, ethnicity and breastfeeding duration are early life predictors of rapid weight gain. Importantly, breastfeeding is a potentially modifiable predictor that may form the basis of targeted prevention efforts to reduce the risk of obesity.
