Proximity To Nearest Major Road And Time To Pregnancy In The Early Pregnancy Study
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Purpose: Current literature suggests that air pollution may affect reproductive outcomes, but little research has evaluated the association between air pollution and fertility. Our aim is to further examine the relationship between distance to major roadway, a proxy for traffic-related air pollution, and fecundability.
Methods: Our analysis was conducted within the North Carolina Early Pregnancy Study (n=221). Our outcome was pregnancy attempt time, an estimate of fecundability, or the per cycle probability of conception. Our primary definition of conception included early pregnancy loss, spontaneous miscarriage, ectopic and molar pregnancy, and singleton or twin pregnancies. In a secondary analysis, we defined conception as clinical pregnancy, which excluded early pregnancy loss. Residential proximity to nearest major road was calculated for each participant. We used general linear regression models to estimate fecundability ratios (FR) according to road proximity. We also used a logistic regression to estimate odds ratios (OR) for the risk of early loss within our proximity metrics. We adjusted for male and female age, education, occupation, and income.
Results: In our primary analysis of all conceptions, fecundability may be slightly improved for couples living near a major road (FR range: 1.11 – 1.42). When we evaluated only clinical pregnancies, results were attenuated, suggesting that proximity to nearest major road is not associated with fecundability. In the analysis of early loss, there appeared to be a slightly increased of early loss in women who live less than 200 meters away from a major road (OR: 2.08, 95%CI: 0.85, 5.09) and in women who live between 200 - <500 meters away from a major road>(OR: 1.82, 95%CI: 0.78, 4.24).
Conclusion: We found some evidence that living near a major road may be associated with increased fecundability but there was no clear dose-response pattern. The slight increase in fecundability reflect an increased risk of early losses for participants who live closer to major roads. Further study of this association is warranted.