Comparison of the Effects of Different Growth Standards on Infants in Urban Shanghai: A Cluster-Randomized Controlled Trial
Children’s growth is a continuous process that requires regular assessment and monitoring to ensure healthy development. Growth standards, which provide reference values for weight, height, and other physical measurements, are essential tools for diagnosing abnormal growth patterns early. The World Health Organization (WHO) developed global growth standards in 2006 based on a multicenter study involving healthy children from six countries. These standards are widely adopted worldwide, including in 125 countries, with 25 others, including China, considering their implementation. However, in Shanghai, local growth standards differ significantly from WHO standards, potentially influencing feeding practices and increasing the risk of childhood obesity. This study aimed to compare the effects of the Shanghai growth standards and the WHO 2006 growth standards on infant growth and obesity in urban Shanghai.
The study was conducted as a cluster-randomized controlled trial in two downtown areas of Shanghai, involving 19 community health service centers. The trial ran from November 2013 to December 2015, with randomization performed at the community level. Infants were divided into two groups: the S-group, assessed using the 2005 Shanghai growth standards, and the W-group, assessed using the WHO 2006 growth standards. Measurements of weight and length were taken at 1.0, 2.0, 4.0, 6.0, 9.0, and 12.0 months of age. Based on these measurements, healthcare providers offered clinical consultations to caregivers, including nutritional advice tailored to the infant’s growth trajectory.
A total of 15,019 infants participated in the study, with 6,509 in the W-group and 8,510 in the S-group. The gender distribution was similar between the two groups, with 52.1% boys in the W-group and 51.4% boys in the S-group. The mean birth weights were also comparable, at 3.38 kg in the W-group and 3.37 kg in the S-group. However, the rates of exclusive breastfeeding differed significantly. At 2 months, 55.5% of infants in the W-group were exclusively breastfed, compared to 65.4% in the S-group. By 4 months, these rates dropped to 52.2% in the W-group and 60.7% in the S-group.
The study found significant differences in overweight rates between the two groups. At 9 months, 3.4% of infants in the W-group were overweight, compared to 4.3% in the S-group. By 12 months, the overweight rates were 2.2% in the W-group and 3.8% in the S-group. These differences were statistically significant, indicating that the use of Shanghai growth standards was associated with a higher risk of infant overweight. Additionally, the study analyzed changes in weight-for-age z-score (WAZ), length-for-age z-score (LAZ), and weight-for-length z-score (WLZ) using mixed regression models. The results showed that the WAZ and WLZ values increased more significantly in the S-group compared to the W-group, while the LAZ values were lower in the S-group. This suggests that infants in the S-group experienced greater weight gain but slightly less height gain than those in the W-group.
The findings highlight the potential impact of growth standards on infant feeding practices and obesity risk. In Shanghai, caregivers often overfeed infants perceived as underweight or smaller than the local growth standards, leading to excessive weight gain. This behavior is influenced by cultural factors, including the historical context of China’s One-Child Policy and past famines, which have shaped parental attitudes toward childhood obesity. The higher reference values in the Shanghai growth standards may exacerbate this issue by misclassifying normal-weight infants as underweight, prompting caregivers to overfeed.
The WHO 2006 growth standards, on the other hand, are based on a longitudinal study of healthy, breastfed infants living in optimal conditions. These standards emphasize growth velocity rather than static measurements, providing a more dynamic approach to assessing infant growth. By adopting the WHO standards, healthcare providers can better identify infants at risk of overweight and intervene early. The study demonstrated that the use of WHO standards did not increase the rates of underweight, stunting, or wasting in infants, suggesting that these standards are suitable for urban Shanghai despite differences in growth patterns.
The study also addressed the limitations of the WHO standards in representing the growth of Shanghai infants. While WHO standards are based on a global sample, Shanghai infants tend to be heavier and taller than the WHO median during the first year of life. This discrepancy may be attributed to differences in feeding practices, genetic factors, and environmental conditions. However, the study concluded that the WHO standards are still preferable for reducing the risk of childhood obesity in urban Shanghai, as they promote healthier growth patterns without compromising height gain.
Quality control measures were implemented throughout the study to ensure data accuracy. These included standardized training for healthcare providers, regular calibration of measurement tools, and rigorous data auditing. The study’s protocol was approved by the Ethical Committee of Xinhua Hospital affiliated with Shanghai Jiao Tong University School of Medicine, and informed consent was obtained from all participants.
In conclusion, the adoption of the WHO 2006 growth standards in urban Shanghai can help reduce the risk of infant overweight without increasing the prevalence of undernutrition. While the Shanghai growth standards reflect the local population’s growth patterns, their higher reference values may inadvertently encourage overfeeding and contribute to childhood obesity. The WHO standards provide a more balanced approach to growth assessment, emphasizing healthy growth velocity and early intervention. This study underscores the importance of selecting appropriate growth standards to promote optimal infant development and prevent childhood obesity.
doi.org/10.1097/CM9.0000000000000004
Was this helpful?
1 / 0