Table 2.
Multivariable linear regression analyses of the association between maternal urinary chromium (μg/g cr) and gestational age (days).
| Chromium | All infants | Male infants | Female infants | p-value | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| n | β (95% CI)a | β (95% CI)b | n | β (95% CI)a | β (95% CI)b | n | β (95% CI)a | β (95% CI)b | ||
| Continuous ln-Cr | 7290 | −1.05(−1.19, −0.91) | −0.68(−0.88, −0.48) | 3891 | −1.11(−1.29, −0.92) | −0.71(−0.98, −0.44) | 3399 | −0.95(−1.16, −0.74) | −0.65(−0.95, −0.36) | 0.24d |
| Low (≤1.09) | 2428 | reference | reference | 1292 | reference | reference | 1136 | reference | reference | |
| Medium (1.09–3.76) | 2435 | −0.95(−1.43, −0.49) | −0.67(−1.14, −0.20) | 1263 | −1.20(−1.86, −0.54) | −0.95(−1.60, −0.29) | 1172 | −0.71(−1.39, −0.03) | −0.39(−1.08, −0.28) | |
| High (>3.76) | 2427 | −3.49(−3.97, −3.02) | −2.30(−2.93, −1.67) | 1336 | −3.78(−4.43, −3.13) | −2.50(−3.37, −1.62) | 1091 | −3.12(−3.81, −2.43) | −2.10(−3.01, −1.20) | |
| p for trendc | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 | 0.21e | |||
CI = confidence interval.
aUnadjusted confounders.
bAdjusted for maternal age, education, BMI, parity, pregnancy-induced hypertension and other metals.
c p-values for trend across tertiles of maternal urinary chromium.
d p-value for ln-Cr*sex interaction.
e p-value for Cr tertile*sex interaction.