Table 2. Characteristics of participants in the preterm birth group and control group.
| Preterm group | Control group | P | OR | 95%CI | |||
| n | % | n | % | ||||
| Marital status | |||||||
| Married | 1356 | 97.5 | 1384 | 99.5 | 0.000 | 1.000 | |
| Unmarried | 35 | 2.5 | 7 | 0.5 | 6.600 | 2.577–16.906 | |
| Education | |||||||
| Elementary school or less | 610 | 44.1 | 533 | 38.7 | 0.032 | 1.441 | 1.032–2.012 |
| Middle school | 558 | 40.4 | 585 | 42.5 | 0.776 | 1.048 | 0.760–1.445 |
| University | 125 | 9.1 | 159 | 11.5 | 0.216 | 0.774 | 0.515–1.162 |
| Graduate | 88 | 6.4 | 101 | 7.3 | 1.000 | ||
| Community | |||||||
| Town/city | 961 | 70.6 | 1060 | 77.3 | 0.000 | 0.537 | 0.422–0.683 |
| Village | 400 | 29.4 | 312 | 22.7 | 1.000 | ||
OR: odds ratio; CI: confidence interval.