The effect of trimester specific and pregnancy average total trihalomethane (TTHM) exposure on gestational age among all births
| Δ Gestational age (weeks) | ||||
|---|---|---|---|---|
| TTHM (μg/l) | First trimester | Second trimester | Third trimester | Pregnancy average |
| *Regression coefficients adjusted for infant gender, adequacy of prenatal care, maternal race, maternal education, maternal smoking, maternal age, parity, median household income, previous infant weighing 4000 g or more, previous preterm delivery, and maternal medical history (diabetes, eclampsia, hydramnios, chronic hypertension, hypertension during pregnancy, incompetent cervix, lung disease, renal disease, and uterine bleeding). | ||||
| Crude | ||||
| 0–60 | Reference | Reference | Reference | Reference |
| >60–80 | 0.05 (−0.01 to 0.11) | 0.06 (0.00 to 0.13) | 0.05 (0.00 to 0.10) | 0.07 (0.02 to 0.12) |
| >80 | 0.00 (−0.07 to 0.06) | 0.08 (0.02 to 0.14) | 0.07 (0.02 to 0.13) | 0.07 (0.03 to 0.11) |
| Per each 20 μg/l | 0.02 (0.01 to 0.03) | 0.03 (0.02 to 0.04) | 0.02 (0.01 to 0.03) | 0.02 (0.01 to 0.02) |
| p value | 0.001 | <0.0001 | <0.0001 | 0.003 |
| Adjusted* | ||||
| 0–60 | Reference | Reference | Reference | Reference |
| >60–80 | 0.02 (−0.04 to 0.09) | 0.06 (0.00 to 0.13) | 0.04 (−0.02 to 0.09) | 0.04 (−0.01 to 0.09) |
| >80 | −0.02 (−0.09 to 0.04) | 0.09 (0.02 to 0.15) | 0.05 (0.00 to 0.11) | 0.08 (0.01 to 0.14) |
| Per each 20 μg/l | 0.01 (0.00 to 0.02) | 0.02 (0.01 to 0.03) | 0.01 (0.00 to 0.02) | 0.02 (0.01 to 0.03) |
| p value | 0.07 | <0.0001 | 0.008 | 0.003 |