Traffic pollution, reproductive health, and depressive symptoms in a healthy multiethnic sample of reproductive age women in the Ovarian Aging Study

Objective This study aimed to determine whether exposure to traffic-related air pollution (TRAP) is associated with depressive symptoms while also characterizing the contribution of key explanatory factors related to sociodemographics and health. In addition, it aimed to also explore the role of reproductive health as a pathway through which exposure to TRAP may relate to depressive symptoms. Methods Participants were 688 healthy reproductive-age women in the Ovarian Aging Study. TRAP was derived from distance-weighted traffic counts using residential addresses. Depressive symptoms were assessed by the Center for Epidemiological Studies Depression scale. Explanatory factors were assessed by interview and clinic measures, including demographics (age, race/ethnicity), socioeconomic status (SES) (individual SES, neighborhood SES), general health (smoking, body mass index), and reproductive health (menarcheal age, contraceptive use, parity, menstrual cycle characteristics). Results In cross-sectional, step-wise multivariate regression analyses, greater exposure to TRAP was related to more depressive symptoms (b = 0.779, P = 0.015). Lower individual SES, longer menstrual cycle length, and experiencing change (vs no change) in menstrual cycle length were also related to more depressive symptoms (P's < 0.05). Examination of each model step showed that variance in depressive symptoms was attributable to TRAP (1.2%, P = 0.004), demographics (1.0%, P = 0.217), SES (1.4%, P = 0.007), general health (0.3%, P = 0.356), and reproductive health (2.0%, P = 0.015). Finally, menstrual cycle length, a marker of reproductive health status, partially mediated effects of TRAP on depressive symptoms (indirect effect: b = 0.064, P = 0.020). Conclusions Findings showed that exposure to TRAP is associated with depression, along with SES and reproductive health factors, and that reproductive health may be a pathway through which TRAP relates to depression.