| Although birth defects are a significant cause of infant morbidity and mortality, there is still very limited information about the causes of birth defects. Environmental and occupational factors are commonly related to birth defect clusters; however, the application of spatial analysis on investigating such association is limited. In this study, we investigated the spatial clustering of birth defects and other adverse birth outcomes in Connecticut by adopting the approach "geoadditive" models.;The birth defects data for the years of 2001-04 from the Connecticut Birth Defects Registry (CTBDR) were used. Exposure assessments were performed on traffic and air pollution, organic solvents, and nitrates/nitrites in drinking water to examine their associations with adverse birth outcomes. Covariates identified from the CTBDR including child's sex, maternal race, Hispanic origin, plurality, marital status, season of conception, maternal age, education, alcohol use, tobacco use, and prenatal care, along with exposures to air pollution, organic solvents, and nitrates/nitrites in drinking water were examined in the multivariate models before incorporating in the spatial generalized additive models.;Increased risks were found for air pollution exposure between CO and cleft lip (OR=1.18; 1.08-1.29), between PM10 and neural tube defect (OR=1.15; 1.06-1.24) and tetralogy of Fallot (OR=1.08; 1.02-1.15), and between PM2.5 and low birth weight (OR=1.13; 1.02-1.23). For occupational exposure to organic solvents, increased risks were found between maternal exposure and hypospadias/epispadias (OR=1.11; 1.02-1.20) and patent ductus arteriosus (OR=1.09; 1.01-1.18), and between paternal exposure and Down syndrome (OR=1.08; 1.04-1.13) and tetralogy of Fallot (OR=1.21; 1.15-1.27). Exposures to nitrates in drinking water from a mixed source were associated with increased risks of patent ductus arteriosus (OR=1.24; 1.02-1.50) and premature births (OR=1.14; 1.02-1.29); and exposures to nitrites were associated with increased risks of tetralogy of Fallot from both overall (OR=2.91; 1.74-4.88) and groundwater (OR=2.89; 1.54-5.45) sources. The spatial effects that remained significant were hypospadias/epispadias (P=0.03) and cleft lip (P=0.005), and both neural tube defect (P=0.05) and ventricular septal defect (p=0.05) were at borderline significance level, after controlling for both environmental and occupational factors.;This study examined the environmental and occupational factors in relation to adverse birth outcomes, using existing surveillance data. Exposure assessments were performed on traffic and air pollution, organic solvents, and chemicals in drinking water, as well as a new approach-geoadditive models that considers both health outcomes and risk factors simultaneously while accounting for non-linear covariates under the assumption of additivity. The results of this study warrant future research to examine other risk factors associated with adverse birth outcomes, while considering possible confounders. |
