Table 2.
Percentage of all preterm births (20- < 37 weeks gestation) and third trimester preterm births (28- < 37 weeks gestation) by maternal smoking status, singleton births United States, 2010
| Maternal Smoking Status | N (%) | Preterm (%) 20- < 37 weeks | Preterm (%) 28- < 37 weeks |
|---|---|---|---|
| No trimester smokers | 2,253,887 (90.67) | (7.68) | (7.23) |
| 1st trimester only, low | 28,560 (1.15) | (8.90) | (8.14) |
| 1st trimester only, high | 4909 (0.20) | (8.68) | (7.87) |
| 1st & 2nd trimesters, low | 11,619 (0.47) | (12.99) | (10.58) |
| 1st & 2nd trimesters, high | 2835 (0.11) | (15.38) | (12.57) |
| 2nd & 3rd trimesters, low | 5759 (0.23) | (8.73) | (8.34) |
| 2nd& 3rd trimesters, high | 584 (0.02) | (9.42) | (8.79) |
| All 3 trimesters, low | 130,060 (5.23) | (10.56) | (10.09) |
| All 3 trimesters, high | 47,530 (1.91) | (11.35) | (10.99) |
Low intensity: 1–19 cigarettes/day; high intensity: ≥ 20 cigarettes/day