Table 1. Socio-demographic characteristics of study participants and bivariate modified Poisson regression results for associations with preterm birth; Life-course Influences on Fetal Environments Study 2009-2011, n=1386.
| Term, N=1159 | PTB, N=226 | |||
| N (%)a | N (%)a | RR | 95% CI | |
| Age | ||||
| 18-19 | 102 (8.8) | 14 (6.2) | .83 | .48, 1.45 |
| 20-24 | 354 (30.5) | 73 (32.3) | 1.18 | .85, 1.63 |
| 25-29 | 313 (27) | 53 (23.5) | referent | |
| 30-34 | 223 (19.2) | 43 (19) | 1.12 | .77, 1.61 |
| 35+ | 167 (14.4) | 43 (19) | 1.41 | .98, 2.04 |
| Marital status | ||||
| Single | 543 (47.2) | 102 (45.5) | referent | |
| Married/cohabiting | 607 (52.8) | 122 (54.5) | 1.06 | .83, 1.35 |
| Education (years) | ||||
| ≤12 | 333 (28.7) | 62 (27.4) | .95 | .73, 1.24 |
| >12 | 826 (71.3) | 164 (72.6) | referent | |
| Income | ||||
| <$35,000 | 496 (48.3) | 85 (40.9) | 1.29 | 1.00, 1.66 |
| ≥$35,000 | 530 (51.7) | 123 (59.1) | referent | |
| Time in neighborhood | ||||
| < 24 months | 532 (46.6) | 107 (48.2) | referent | |
| ≥24 months | 609 (53.4) | 115 (51.8) | .95 | .75, 1.21 |
| Study enrollment year | ||||
| 2009 | 228 (19.7) | 49 (21.7) | referent | |
| 2010 | 411 (35.5) | 81 (35.8) | .93 | .67, 1.29 |
| 2011 | 520 (44.9) | 96 (42.5) | .88 | .64, 1.21 |
PTB, preterm birth.
a. Numbers do not add up to 1388; one participant had missing data.