Table 3 Unadjusted and covariate-adjusted^a odds ratios (95 % confidence intervals) for gestational diabetes mellitus versus normal glucose tolerance

First trimester PM_2.5

 Q1 (3.1–9.3 μg/m³)

1.00 (reference)

1.00 (reference)

 Q2 (9.3–10.4 μg/m³)

0.95 (0.88, 1.03)

1.00 (0.93, 1.09)

 Q3 (10.4–11.5 μg/m³)

0.91 (0.84, 0.98)

0.97 (0.89, 1.05)

 Q4 (11.5–17.1 μg/m³)

0.92 (0.85, 1.00)

1.00 (0.92, 1.09)

 10–90 percentile range (4.3 μg/m³)

0.92 (0.86, 0.99)

1.01 (0.93, 1.09)

Second trimester PM_2.5

 Q1 (1.3–9.2 μg/m³)

1.00 (reference)

1.00 (reference)

 Q2 (9.2–10.4 μg/m³)

0.98 (0.91, 1.06)

1.04 (0.96, 1.13)

 Q3 (10.4–11.6 μg/m³)

0.90 (0.83, 0.97)

0.95 (0.88, 1.03)

 Q4 (11.6–19.3 μg/m³)

0.98 (0.9, 1.05)

0.99 (0.91, 1.08)

 10–90 percentile range (4.5 μg/m³)

0.96 (0.89, 1.03)

0.97 (0.90, 1.05)

Traffic density^d

 Q1 (0–280)

1.00 (reference)

1.00 (reference)

 Q2 (280–744)

1.02 (0.95, 1.10)

1.04 (0.96, 1.12)

 Q3 (744–1,636)

0.99 (0.91, 1.07)

1.01 (0.93, 1.10)

 Q4 (1,636–37,306)

1.01 (0.93, 1.09)

1.03 (0.95, 1.12)

 10–90 percentile range (2,799)

1.00 (0.96, 1.04)

1.00 (0.97, 1.04)