Effects of two standards on the overweight trend of infants and toddlers in urban Shanghai / 中华儿科杂志

ABSTRACT

Objective@#To observe and compare the effects of two standards on the overweight trend in urban Shanghai infants and young children.@*Methods@#A cluster randomized controlled trial was conducted in 19 communities in two districts of Shanghai, and the subjects (n=15 019) were divided into S-group and W-group by sealed envelope randomization. The subjects were newborns born between November 2013 and December 2014. The 2005 Shanghai growth standard was applied in the S-group and the 2006 WHO growth standard was used in the W-group. At each follow-up time point age of 1, 2, 4, 6, 9, 12 and 18 months, the outpatient physician assessed the length and weight of the infants according to the standard adopted by each group and provided feeding guidance. The weight-for-age Z scores (WAZ), length-for-age Z scores (LAZ) and weight-for-length Z scores (WLZ) were calculated according to the WHO standard. Weight, length, WAZ, LAZ, WLZ and overweight ratio (WLZ≥2) were compared between the two groups using t test, Wilcoxon test and χ2 test.@*Results@#A total of 6 509 infants (3 391 were boys, 3 118 were girls) were in the W-group, and 8 510 infants (4 374 were boys, 4 136 were girls) were in the S-group. Among the boys, the weight values at the age of 4, 6, 9, 12, 18 months in the W-group were all lower than those in the S-group ((7.5±0.8) vs. (7.7±0.8) kg, (8.6±0.8) vs. (8.7±0.8) kg, (9.6±0.9) vs. (9.7±0.9) kg, (10.4±1.0) vs. (10.5±1.0) kg, (11.5±1.1) vs.(11.7±1.1) kg; t=4.329, 2.422, 3.739, 2.451, 2.736; P<0.01, 0.015,<0.01, 0.014, 0.009). The length had no significant difference between two groups at all months of age(all P>0.05). The overweight ratio in the W-group was lower than that in the S-group at the age of 9, 12, 18 months(3.3% (71/2 170) vs. 4.9% (143/2 927), 2.5% (51/2 037) vs. 4.5% (126/2 818), 0.8% (7/832) vs. 3.1% (39/1 266); χ2=6.520, 14.209, 12.350; P=0.011,<0.01,<0.01).Among the girls, except at the age of 2 months (W-group (5.6±0.6) vs. S-group (5.7±0.6), t=2.935, P=0.003), weight values had no significant difference between the two groups at other age months (all P>0.05).The length in the W-group was higher than that in the S-group at 12 and 18 months of age ((75.6±2.4) vs.(75.5±2.3)cm, (82.4±2.9) vs.(82.2±2.7) cm; t=2.351, 2.197; P=0.019, 0.028). The ratio of overweight in the W-group was lower than that of S-group at the age of 12 and 18 months (1.8% (33/1 871) vs.3.0% (80/2 658), 0.6% (5/790) vs.1.7% (20/1 178); χ2=6.764,4.276; P=0.009, 0.039).@*Conclusions@#The application of WHO growth standard can help to reduce the weight gain rate of boys, promote the linear growth of girls, and thus alleviate the overweight trend of infants within 18 months. It suggested that 2006 WHO growth standard should be applied to infants within 1 year of age in Shanghai.