Cesarean section and association with intelligence quotient in adolescents: contribution from the RPS Cohort Consortium (Ribeirão Preto, Pelotas and São Luís), Brazil

This study aimed to evaluate the association between cesarean section and intelligence quotient (IQ) in adolescents from the Municipality of São Luís, Maranhão State, Brazil. This is a longitudinal study using data from the São Luís birth cohort, started in 1997. The approach occurred in the third phase of the cohort, in 2016, with adolescents aged 18 and 19 years. The exposure variable was mode of delivery and the outcome variable was IQ, measured by applying the third version of the Wechsler Adult Intelligence Scale (WAIS-III). In the data analysis, the average IQ was verified according to the covariates and multivariate linear regression was used. To control confounding factors, a theoretical model was elaborated using the directed acyclic graph. The confounding variables were socioeconomic variables at birth and perinatal variables. Their average IQ was 101.4. In the crude analysis, the IQ of adolescents born by cesarean section was 5.8 points higher than those born by vaginal delivery (95%CI: 3.8; 7.7, p ≤ 0.001), with statistical significance. In the multivariate analysis, the value decreased to 1.9 (95%CI: -0.5; 3.6, p = 0.141), without statistical significance. The result of the study showed that cesarean section is not associated with the IQ of adolescents in this sample and reflects that the differences can be explained by other factors, such as socioeconomic and perinatal aspects.