Table 1.

Maternal demographic and clinical characteristics in the study area (N = 195,500)

	n (%)
Age-group
<20 year	6431 (3.3)
20 – <35 years	149,762 (76.6)
35+ years	39,307 (20.1)
Country of birth
Australian	106,769 (54.6)
Overseas	88,731 (45.4)
Index of Relative Socio-economic Disadvantage
(missing = 1,883)
Most disadvantage	64,541 (33.3)
Middle disadvantage and Least disadvantage	129078 (66.7)
Number of babies
Multiple	5,886 (3.0)
Singleton	189,614 (97.0)
Primiparous (missing = 448)
Yes	83,263 (42.6)
No	111,789 (57.2)
First antenatal visit (missing = 3,049)
≥10 weeks	60,041 (30.7)
<10 weeks	132,410 (67.7)
Smoking during pregnancy (missing = 1,613)
Yes	22,635 (11.6)
No	171,252 (87.6)