The frequency of maternal exposure to total trihalomethane (TTHM) concentration during pregnancy
| TTHM (μg/l) | First trimester | Second trimester | Third trimester | Pregnancy average |
|---|---|---|---|---|
| 0–60 | 46366 (82%) | 45746 (81%) | 44556 (79%) | 44232 (78%) |
| >60–80 | 5308 (9%) | 5085 (9%) | 5964 (11%) | 7588 (13%) |
| >80 | 4339 (9%) | 5682 (10%) | 5721 (10%) | 4693 (8%) |