Racial inequality in perinatal outcomes in two Brazilian birth cohorts

This study aimed to estimate and compare racial inequality in low birth weight (LBW), preterm birth (PTB), and intrauterine growth restriction (IUGR) in two Brazilian birth cohorts. This was a cross-sectional study nested within two birth cohorts in Ribeirão Preto (RP) and São Luís (SL), whose mothers were interviewed from January to December 2010. In all, 7430 (RP) and 4995 (SL) mothers were interviewed. The maternal skin color was the exposure variable. Associations were adjusted for socioeconomic and biological covariates: maternal education, per capita family income, family economic classification, household head occupation, maternal age, parity, marital status, prenatal care, type of delivery, maternal pre-pregnancy BMI, hypertension, hypertension during pregnancy, and smoking during pregnancy collected from questionnaires applied at birth. Statistical analysis was done with the chi-squared test and logistic regression. In RP, newborns from mothers with black skin color had a higher risk of LBW and IUGR, even after adjusting for socioeconomic and biological variables (P<0.001). In SL, skin color was not a risk factor for LBW (P=0.859), PTB (P=0.220), and IUGR (P=0.062), before or after adjustment for socioeconomic and biological variables. The detection of racial inequality in these perinatal outcomes only in the RP cohort after adjustment for socioeconomic and biological factors may be reflecting the existence of racial discrimination in the RP society. In contrast, the greater miscegenation present in São Luís may be reflecting less racial discrimination of black and brown women in this city.

Do socioeconomic factors explain why maternal smoking during pregnancy is more frequent in a more developed city of Brazil?

The prevalence of smoking during pregnancy in Ribeirão Preto, a rich Brazilian city, was significantly higher (21.4 percent) than in São Luís (5.9 percent), a less developed city. To assess which variables explain the difference in prevalence of smoking during pregnancy, data from two birth cohorts were used, including 2846 puerperae from Ribeirão Preto, in 1994, and 2443 puerperae from São Luís, in 1997/98. In multivariable analysis, risk of maternal smoking during pregnancy was higher in São Luís for mothers living in a household with five or more persons (OR = 1.72, 95 percentCI = 1.12-2.64), aged 35 years or older (OR = 1.98, 95 percentCI = 0.99-3.96), who had five or more children (OR = 2.10, 95 percentCI = 1.16-3.81), and whose companion smoked (OR = 2.20, 95 percentCI = 1.52-3.18). Age of less than 20 years was a protective factor (OR = 0.55, 95 percentCI = 0.33-0.92). In Ribeirão Preto there was association with maternal low educational level (OR = 2.18, 95 percentCI = 1.30-3.65) and with a smoking companion (OR = 3.25, 95 percentCI = 2.52-4.18). Receiving prenatal care was a protective factor (OR = 0.24, 95 percentCI = 0.11-0.49). Mothers from Ribeirão Preto who worked outside the home were at a higher risk and those aged 35 years or older or who attended five or more prenatal care visits were at lower risk of smoking during pregnancy as compared to mothers from São Luís. Smoking by the companion reduced the difference between smoking rates in the two cities by 10 percent. The socioeconomic variables in the model did not explain the higher prevalence of smoking during pregnancy in the more developed city.