Particulate Air Pollution Exposure and Plasma Vitamin D Levels in Pregnant Women: A Longitudinal Cohort Study.

CONTEXT

No studies have assessed the association between air pollution exposure and vitamin D status in pregnant women.

OBJECTIVE

To examine the association between particulate air pollution exposure and circulating 25-hydroxyvitamin [25(OH)D] levels in pregnant women.

DESIGN

A longitudinal cohort study.

PARTICIPANTS

A total of 3285 pregnant women were recruited at a maternal and child health hospital.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Serum 25(OH)D levels.

RESULTS

We observed trimester-specific associations between particulate air pollution exposure and circulating 25(OH)D levels. The associations were most pronounced for the periods of the third trimester and the entire pregnancy. A 10 μg/m3 increase in fine particulate matter (PM2.5) and particulate matter with aerodynamic diameter ≤10 μm (PM10) exposure during the entire pregnancy was associated with a 4.62% (95% CI, -6.31% to -2.93%) and 5.06% (95% CI, -6.50% to -3.62%) decrease in 25(OH)D levels, respectively. Particulate air pollution exposure was also associated with elevated odds of maternal vitamin D deficiency. A 10 μg/m3 increase in PM2.5 and PM10 exposure during the entire pregnancy was associated with a 45% (OR = 1.45, 95% CI, 1.29 to 1.63) and 48% (OR = 1.48, 95% CI, 1.33 to 1.64) increase in the odds of maternal vitamin D deficiency. Mediation analysis estimated that decreased solar UV-B radiation mediated 69.5% and 66.4% of the inverse association between PM2.5 and PM10 exposure and circulating 25(OH)D levels.

CONCLUSION

Our results suggest that prenatal exposure to particulate air pollution may play an independent role in maternal vitamin D deficiency. The role of air pollution should be incorporated into future guidelines for the prevention of maternal vitamin D deficiency.