Table 1 Characteristics at the first birth of the study population of mothers who gave birth to their first two singleton children between 1994 and 2016 in New South Wales (N = 517,558 mothers)
From: Gestational age as a predictor for subsequent preterm birth in New South Wales, Australia
All | Term | Preterm | |
|---|---|---|---|
N (%) | N (%) | N (%) | |
All | 517,558 (100) | 487,041 (94.1) | 30,517 (5.9) |
Maternal Age | |||
< 20 years | 44,818 (8.7) | 41,588 (8.5) | 3230 (10.6) |
20–24 years | 111,386 (21.5) | 104,945 (21.5) | 6441 (21.1) |
25–29 years | 181,503 (35.1) | 171,489 (35.2) | 10,014 (32.8) |
30–34 years | 138,676 (26.8) | 130,624 (26.8) | 8052 (26.4) |
35–39 years | 38,307 (7.4) | 35,780 (7.3) | 2527 (8.3) |
≥ 40 years | 2737 (0.5) | 2492 (0.5) | 245 (0.8) |
Missing | 131 (< 0.1) | 123 (< 0.1) | 8 (< 0.1) |
Ethnicity | |||
Aboriginal or Torres Strait Islander a | 9883 (1.9) | 8982 (1.8) | 901 (3.0) |
Non-Aboriginal | 410,248 (79.3) | 386,295 (79.3) | 23,953 (78.5) |
Missing | 97,427 (18.8) | 91,764 (18.8) | 5663 (18.6) |
Smoked during pregnancy b | |||
No | 453,201 (87.6) | 427,638 (87.8) | 25,563 (83.8) |
Yes | 63,284 (12.2) | 58,419 (12.0) | 4865 (15.9) |
Missing | 1073 (0.2) | 984 (0.2) | 89 (0.3) |
Year of birth | |||
1994–1999 | 145,603 (28.1) | 137,052 (28.1) | 8551 (28.0) |
2000–2004 | 124,706 (24.1) | 117,300 (24.1) | 7406 (24.3) |
2005–2009 | 134,350 (26.0) | 126,505 (26.0) | 7845 (25.7) |
2010–2016 | 112,899 (21.8) | 106,184 (21.8) | 6715 (22.0) |
Small for gestational age | |||
No | 453,865 (87.7) | 427,054 (87.7) | 26,811 (87.9) |
Yes | 63,214 (12.2) | 59,616 (12.2) | 3598 (11.8) |
Missing | 479 (0.1) | 371 (0.1) | 108 (0.4) |
Stillbirth | |||
No | 514,568 (99.4) | 486,070 (99.8) | 28,498 (93.4) |
Yes | 2990 (0.6) | 971 (0.2) | 2019 (6.6) |
Socioeconomic Index c | |||
Missing | 4103 (0.8) | 3880 (0.8) | 223 (0.7) |
Mean (SD) d | 997 (66) | 997 (66) | 993 (65) |