Objective: To explore the effect of breastfeeding duration on age at adiposity rebound, and provide a scientific theoretical basis for identifying early life factors of obesity in children and adolescents, while promoting early intervention. Methods: In September 2019, first graders from a primary school in Minhang District, Shanghai, were selected to participate in this study, and their growth information was retrospectively collected. The natural cubic spline function was used to fit the body mass index trajectory of the subjects from 1 to 80 months, and age at adiposity rebound was calculated. A total of 6 148 subjects were selected, and complete data of adiposity rebound timing and breastfeeding duration were obtained. A multiple linear regression model was used to analyze the relationship between these two variables. Results: The average breastfeeding duration of all children included in the study was (3.71±3.28) months, and most of the subjects (69.63% for male and 70.45% for female) were breastfed for less than 4 months. A positive linear relationship was found between them [male, B =0.16(0.02-0.30), female, B =0.34(0.18- 0.51 ), total, B =0.23(0.12-0.34), P <0.05]. The linear relationship was determined using the multivariate model. Conclusion Breastfeeding duration independently affected age at adiposity rebound. Prolonging the duration of breastfeeding within 24 months of age may help to delay the timing of adiposity rebound,and thus reduce later risks of overweight and obesity.

Objective: To explore the characteristics of the adiposity peak and rebound in early life among first year primary school students with different body weight measures, so as to provide scientific evidence for the development of prevention interventions to manage childhood overweight and obesity. Methods: A total of 2 330 first year primary school students who received routine physical examinations from September to December in 2019 were selected. According to body mass index (BMI) status, participants were divided into three categories:healthy weight, overweight, and obese. The BMI growth trajectories of the three groups were fitted by gender using the generalized additive mixed model from 1 to 80 months, retrospectively. Each subject s age at the adiposity peak and rebound, and associated BMI values, were calculated. Results: The prevalence of overweight and obesity was 16.31 % (380/ 2 330 ) and 16.09% (375/2 330), respectively. For first year students with obesity, the BMI value continued to be higher than their overweight or healthy weight counterparts during the first 80 months of life. The age at the adiposity peak for these students, whose BMI status varied, was about nine months. However, the BMI of children with overweight or obesity was much higher than that of healthy weight subjects. Age at adiposity rebound was 72 months for healthy weight children, 52 to 55 months in children defined as overweight, and 22 to 23 months in children with obesity. For healthy weight children, the fitted value of BMI at the adiposity rebound was less than that of overweight and obese children. Conclusion Age at the adiposity peak was largely similar among first year students with different BMI patterns; however, age at adiposity rebound was different. Age at adiposity rebound among children with obesity was much earlier than that of other subjects, and their BMI values were much higher.