Secular trends of birth weight and its associations with obesity and hypertension among Southern Chinese children and adolescents

The association of low or high birth weight (L/HBW) with obesity and hypertension in childhood remains unclear. We aimed to identify the secular trend of birth weight distribution and its relationship to obesity and hypertension in Southern Chinese children and adolescents.6,561 individuals (6-17-year-old) were enrolled by multistage cluster sampling to observed the trend of birth weight distribution and its associated factors. 1,218 were further selected by group matching to investigate the correlation between birth weight and obesity or hypertension.Between 1997 and 2008, a significant decline in the LBW rate and no significant change in the HBW rate was found. LBW was associated with maternal BMI<18 kg/m2 (OR1.79, 95% CI 1.08-2.97) during pregnancy, while maternal BMI between 25.0 and 27.9 kg/m2 (OR1.62, 95% CI 1.04-2.52) and paternal BMI>28 kg/m2 (OR1.64, 95% CI 1.02-2.63) during pregnancy were associated with HBW. The prevalence of obesity was significantly higher with HBW than normal birth weight (NBW) or LBW (16.73, 6.25 and 5.50%, respectively). The prevalence rates of suspected hypertension were 1.62, 1.25 and 1.49% among LBW, NBW and HBW, respectively (p>0.05). LBW decreased the risks of childhood overweight (OR0.31, 95% CI 0.18-0.54), but had no effect on suspected hypertension. HBW increased the risks of childhood obesity (OR2.19, 95% CI 1.50-3.20), but decreased the risks of suspected hypertension (OR0.22, 95% CI 0.09-0.58).HBW was positively associated with childhood obesity, and parental BMIs management might be one of the measurements to control birth weight to lessen childhood obesity.