Socioeconomic determinants of low birth weight and their association with peripubertal obesity in Brazil

Fernanda Lima-Soares ^1,2 Renato Simões Gaspar ³ Silas Alves-Costa ⁴ Cecilia Claudia Costa Ribeiro ⁴ Antonio Marcus de Andrade Paes ^1,2*

• ¹ Laboratory of Experimental Physiology, Department of Physiological Sciences, Biological and Health Sciences Centre. Federal University of Maranhão., São Luís, MA, Brazil
• ² Health Sciences Graduate Program, Biological and Health Sciences Centre, Federal University of Maranhão., São Luís, MA, Brazil
• ³ Department of Translational Medicine, Universidade Estadual de Campinas., Campinas, SP., Brazil
• ⁴ Graduate Program in Dentistry, Biological and Health Sciences Centre, Federal University of Maranhão., São Luís, MA., Brazil

Introduction: Low birth weight (LBW) is an early life adversity associated with several risk factors and metabolic dysfunction over the lifespan. However, the role of socioeconomic factors in the association between LBW and peripubertal health in low- and middle-income countries (LMICs) remains unclear. This ecological study investigated factors contributing to LBW and its repercussions in Brazil. Methods: Data were collected from the Global Health Data Exchange as summary exposure value (SEV), a surrogate of populational prevalence weighted by the relative risk, and from official sources of Brazilian government from 1995 to 2017, totaling 338 state-year observations applied for temporal lagged analyses. First, we tested the SEV of 1-year lagged reproductive-age population (15–49 years) risk factors as exposures and the SEV of LBW as an outcome. Next, in a second temporal lagged analysis, we tested the association between SEV LBW as the primary exposure and SEV high body mass index (HBMI) in peripubertal ten years later as the outcome. Fixed-effects multivariable linear regression models with lags were constructed, adjusting for socioeconomic covariates. Results: Reproductive-age population exposure to smoking, alcohol, high systolic blood pressure, and HBMI were positively associated with SEV LBW. Diet high in sugar-sweetened beverages was also positively associated, but the association was lost when GDP per capita and primary care were added to the model. Regarding repercussions of LBW, a 1-point increase in SEV LBW was associated with a 1.6-point increase in HBMI in the peripubertal population (95% CI: 0.66 to 2.55). However, this association disappeared after adjusting for GDP per capita and access to primary care, indicating their confounding role. Discussion: Our study indicates several risk factors of the adult population associated with LBW and its association with peripubertal HBMI. Interestingly, GDP per capita and access to primary care were shown to be determinant socioeconomic covariates for birth outcomes of exposure to the risk factors tested and to the mid-term effects of LBW. These findings enhance our understanding of how socioeconomic factors contribute to LBW in LMICs and the need for public policies addressing healthcare and welfare to reduce the burden of LBW in LMICs.