Temporal trends in birthweight and its association with overweight/obesity in schoolchildren from a Brazilian city: a cross-sectional panel study (2002-2019).

BACKGROUND: Long-term metabolic complications in childhood are associated with birthweight. OBJECTIVES: This study aimed to examine trends in the prevalence of low and high birthweight over a 16-year period and to investigate the association between birthweight and overweight/obesity among schoolchildren aged 7 to 10 years. DESIGN AND SETTING: The analyses included four school-based cross-sectional surveys conducted in Florianópolis. METHODS: The probabilistic panels were conducted in 2002, 2007, 2012-2013, and 2018-2019. Multiple logistic regression models were used to assess the associations between low and high birthweight and childhood overweight/obesity. Adjusted models included biological, socioeconomic, survey-period, and dietary-intake variables. RESULTS: Over the 16-year period, low birthweight showed a progressive and statistically significant increase, rising by 58.3% from 2002 to 2018-2019. In contrast, the prevalence of high birthweight was 9.1% in 2002 and declined significantly over the ten-year period from 2002 to 2012-2013, decreasing by 40.7%. In the adjusted model, high birthweight was significantly associated with overweight/obesity across all study waves (OR = 1.63; 95% CI = 1.32-2). CONCLUSION: A statistically significant upward trend in the prevalence of low birthweight was observed among schoolchildren in Florianópolis from 2002 to 2018-2019. Despite a reduction in high birthweight over time, high birthweight remained directly associated with overweight/obesity, independently of food intake and other confounding factors.