Variables | Preterm (%) N = 5969 | Full-term (%) N = 124,393 | P-value |
---|---|---|---|
Parity |  |  | < 0.0001 |
 Multiparous | 2767 (46.4) | 61,371 (49.3) |  |
 Nulliparous | 3202 (53.6) | 63,022 (50.7) |  |
Multiplicity |  |  | < 0.0001 |
 Singleton | 5595 (93.7) | 123,797 (99.5) |  |
 Multifetal births | 374 (6.3) | 596 (0.5) |  |
Maternal age (years) |  |  | < 0.0001 |
 < 20 | 19 (0.3) | 408 (0.3) |  |
 20–39 | 4655 (78.0) | 106,746 (85.8) |  |
 ≥ 40 | 1295 (21.7) | 17,239 (13.9) |  |
History of preterm birth |  |  | < 0.0001 |
 No | 5897 (98.8) | 124,244 (99.9) |  |
 Yes | 72 (1.2) | 149 (0.1) |  |
History of maternal drug abuse/dependence | Â | Â | 0.0002 |
 No | 206 | 124,187 |  |
 Yes | 24 | 5945 |  |
Maternal medical disorders | Â | Â | < 0.0001 |
 No | 5050 (84.6) | 118,169 (95.0) |  |
 Yes | 919 (15.4) | 6224 (5.0) |  |