Maternal Exposure to Outdoor Air Pollution and Congenital Limb Deficiencies in National Birth Defects Prevention Study

摘要

Background Congenital limb deficiencies (CLDs) are a relatively common phenotypic grouping of birth defects. Emerging evidence from recent studies suggests air pollutants as potential risk factors. Aim To investigate the relationship between ambient air pollution during early pregnancy and CLDs. Methods During 1997-2007, 595 cases of CLDs and 5,432 controls were identified from the National Birth Defects Prevention Study, a multi-center population-based case-control study. Weekly and overall averages of 6 criteria air pollutants (particulate matter <2.5μg/m3 [PM2.5], PM10, nitrogen dioxide [N02], sulfur dioxide [S02], carbon monoxide [CO], and ozone [03]) during gestational weeks 2-8 were estimated with EPA air monitors nearest to the maternal address recorded at birth. Logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs), considering potential confounders: maternal age, race/ethnicity, education, and study center. We additionally analyzed CLD subtypes (i.e., transverse, longitudinal, and intercalary), assessed modification by body mass index, cigarette smoking, folic acid use, and distance to air monitor, and adjusted for co-pollutants. Results We observed near-null adjusted associations between CLDs and PM10, PM2.5, and O3. However, weekly averages of the daily NO2 and SO2, and daily maximum 1-hour CO concentrations were associated with increased odds of CLDs. The largest and most consistent effect was in CO (week 2 aOR: 1.13 per 1 ppm change, 95% CI: 1.00-1.27), with similar trends for CLD subtypes. The aORs for CO were elevated if mothers did not use folic acid or lived within 20km of an air monitor. The aORs for SO2 were elevated if mothers were obese or were smokers. In co-pollutant models, CO was associated with elevated odds of CLDs (aORs: 1.02-1.30) and aORs for S02 and NO2 were attenuated. Conclusion CO may be associated with CLDs, and further epidemiologic and mechanistic research is warranted. Disclaimer The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency, the Centers for Disease Control and Prevention, or the California Department of Public Health.