China: Findings from a recent study showed that low socioeconomic status (SES) is associated with increased body mass index (BMI) and accelerated growth during early infancy in infants with low birth weight (LBW).
The study, published in the journal BMC Pediatrics, suggests that health care and a relatively optimal family environment in the first 12 months of life are beneficial for better infancy growth trajectory, particularly for LBW infants. This implies that poverty in urban areas should be a potential predictor of later obesity.
Obesity and overweight during childhood is an epidemic increasing public concerns and is related to poorer physical and mental health outcomes later in life. Previous studies have reported the association of low socioeconomic status with childhood and adolescent obesity. Whether low SES affects BMI growth trajectory in the first 12 mo of life is still not known. Also, accelerated growth as a compensatory mechanism for LBW is an important predictor of later obesity.
Against the above background, Peng Zhu, Anhui Medical University, Hefei, China, and colleagues aimed to examine the association of low SES with infancy BMI growth rate and trajectory for LBW and normal birth weight (NBW) infants.
For the study, a total of 387 infants were subjected to repeated measures of weight and length from birth to 12 mo in Hefei from September 2012 to October 2014. The infancy BMI growth trajectories were classified using generalized growth mixture modeling. Differences in infancy BMI z score (zBMI) and BMI growth rate between low SES and high SES were estimated.
Key findings include:
· Infancy BMI trajectories in this study were classified into three categories: rapid growth (class 1), normal growth (class 2), and slow growth (class 3).
· Low SES infants had the higher zBMI than high SES infants for the LBW group at age 6 mo [zBMI difference at 6 mo: 0.28; at 12 mo: 0.21].
· Low SES infants had a more rapid zBMI growth rate than those with high SES for low birth weight between 0 and 6 months.
· Controlling for the confounders, these associations remained robust.
· The lower SES was found in the rapid growth group.
Based on the findings, the authors concluded that health care and relatively optimal family environment in the prenatal and early postnatal period, especially for LBW infants, are essential to establish a better growth trajectory for preventing and intervening the later overweight or obesity.
Reference:
Shao, Zy., Wang, P., Li, P. et al. Socioeconomic disparities and infancy growth trajectory: a population-based and longitudinal study. BMC Pediatr 21, 549 (2021). https://doi.org/10.1186/s12887-021-02995-4