Comparison of the effects of different growth standards on infants in Urban Shanghai: a cluster-randomized controlled trial

BACKGROUND: The Shanghai growth standards are higher than World Health Organization (WHO) growth standards, which may influence the feeding practices of the caregivers and increase the risk of overweight in these infants. This study aimed to compare the effects of different growth standards on childhood obesity in Shanghai metropolitan area. METHODS: This was a cluster-randomized controlled trial conducted in 2 downtown areas with 19 community health service centers in Shanghai from November 2013 to December 2015. Randomization was done at the level of the community. Infants (health newborns) were assessed and monitored by the Shanghai growth standards (S-group) and the 2006 WHO growth standards (W-group), respectively. Measurements were taken at 1.0, 2.0, 4.0, 6.0, 9.0 and 12.0 months of age during follow-up period. Based on the values of length and weight measurements, according to the group's growth standards, doctors provided the caregivers with corresponding clinical consultation. Changes in weight-for-age z-score (WAZ), length-for-age z-score (LAZ), and weight-for length z-score (WLZ) between 2 groups were assessed using mixed regression models. Overweight was compared between 2 group at all follow-up measurements. RESULTS: A total of 6509 infants (52.1% were boys) were in the W-group, and 8510 infants (51.4% were boys) were in the S-group. The overweight ratios between two groups were distinct at 9 months of age (3.4% in W-group and 4.3% in S-group) and 12 months of age (2.2% in W-group and 3.8% in S-group), and the differences were statistically significant (P = 0.020 and P < 0.001, respectively). Compared to W-group, the increase in WAZ (coefficient = 0.04, P = 0.004) and WLZ (coefficient = 0.09, P < 0.001) were significantly greater, and the LAZ was lower (coefficient = −0.04, P = 0.047) in S-group (W-group values were used as reference in mixed regression models). CONCLUSION: Compared to the Shanghai growth standards, the adoption of WHO 2006 growth standards would reduce the risk of infant overweight in Shanghai metropolitan area up to 1 year of age. TRIAL REGISTRATION NUMBER: ChiCTR1800015371, http://www.chictr.org.cn/ Chinese Clinical Trial Registry.