Maternal exposure to sulfur dioxide before and after conception and the risk of hypospadias in offspring.

As far as we know, there have been no studies exploring the association between maternal sulfur dioxide (SO2 ) exposure and the risk of hypospadias in offspring. We aimed to evaluate this association during the 3 months before conception and the first trimester. A population-based case-control study was conducted in male infants, consisting of 348 cases of hypospadias and 4023 controls. Maternal exposure to SO2 , particulate matter with aerodynamic diameters ≤10 μm (PM10 ), and nitrogen dioxide (NO2 ) was assessed by averaging the concentrations recorded at all stations in the mother's city of residence. Air pollutants were tested for multicollinearity using variance inflation factor analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by multivariable logistic regression models. SO2 exposure during the 3 months before conception was significantly associated with the risk of hypospadias (highest tertile: OR = 7.40, 95% CI: 3.54-15.62). When focusing on shorter exposure windows, similar associations were observed for SO2 exposure in the first and second month before and the first month after conception. In conclusion, maternal exposure to SO2 during the 3 months before and the first and second months after conception may increase the risk of hypospadias in offspring.