Table 1. Maternal characteristics and birth outcomes and relative change throughout the study period, 1994–2009.
| 1994 N (%) | 1999 N (%) | 2004 N (%) | 2009 N (%) | Relative change§(%) | |
| All mothers | 86,463 | 85,961 | 84,283 | 95,033 | 9.9 |
| Maternal age (years) | |||||
| <20 | 4,358 (5.1) | 4,098 (4.8) | 3,387 (4.0) | 3,292 (3.5) | −31.4 |
| 20–34 | 70,680 (81.8) | 67,167 (78.2) | 64,110 (76.1) | 69,068 (72.7) | −11.1 |
| 35+ | 11,313 (13.1) | 14,668 (17.1) | 16,769 (19.9) | 22,658 (23.8) | 81.7 |
| Nulliparous | 34,194 (39.5) | 35,308 (41.1) | 35,795 (42.5) | 40,345 (42.4) | 7.3 |
| Non-Australian born | 22,587 (25.9) | 23,728 (27.2) | 23,471 (27.5) | 30,278 (31.5) | 21.6 |
| Multiple birth | 1,212 (1.4) | 1,291 (1.5) | 1,305 (1.5) | 1,366 (1.4) | 0 |
| Low risk women† | 51,084 (59.1) | 47,018 (54.7) | 45,313 (53.8) | 48,286 (50.8) | −14.0 |
| Preterm birth | 5,067 (5.9) | 5,562 (6.5) | 5,553 (6.6) | 6,302 (6.6) | 11.9 |
| Private hospital | 13,357 (15.4) | 15,869 (18.5) | 20,551 (24.4) | 23,478 (24.7) | 60.4 |
| Labour induction | 17,536 (20.3) | 20,612 (24.0) | 20,549 (24.4) | 24,473 (25.7) | 26.6 |
| Pre-labour caesarean section | 8,055 (9.3) | 9,147 (10.6) | 12,929 (15.3) | 16,649 (17.5) | 88.2 |
| All babies * | 87,705 | 87,283 | 85,621 | 96,429 | 9.9 |
| Livebirths | 86,980 (99.2) | 86,734 (99.4) | 85,056 (99.3) | 95,827 (99.4) | 0.2 |
| Stillbirths | 494 (0.56) | 533 (0.61) | 561 (0.66) | 598 (0.62) | 10.1 |
§
Relative change was calculated by: [(2009 rate –1994 rate)/(1994 rate)].
*
100; Test-for-trend was significant for all factors except stillbirths and multiple births, P<0.001.
†
Low risk pregnancies defined as primiparae, aged 20–34 years, without pregnancy complications; and with a liveborn singleton infant, born in cephalic presentation and of normal fetal growth at the 10th–90th birth weight percentile of the distribution for gestational age and infant sex. [16].
*
Numbers may not add up to totals due to missing data or rounding.