Risk factors associated with preterm birth among singletons following assisted reproductive technology in Australia 2007–2009–a population-based retrospective study

Table 1 Sociodemographic characteristics of singleton birth mothers by ART status, Australia, 2007–2009

	Non-ART		ART		P
	(N = 381,345)		(N = 12,105)		P
	No.	%	No.	%
Maternal age (years)
Mean ± SD	29.7 ± 5.7		34.0 ± 4.8		<0.01
Less than 24	76,182	20.0	267	2.2	<0.01
25–34	223,494	58.6	6,131	50.7
35–44	81,216	21.3	5,535	45.7
45 and over	439	0.1	172	1.4
Maternal country of birth
Australia	294,196	77.6	9,671	80.2	<0.01
Overseas	85,083	22.4	2,389	19.8
BMI (kg/m ² ) ^(a)
Less than 18.5	4,749	4.3	163	3.9	<0.01
18.5–24.9	49,913	45.6	2,079	49.7
25.0–29.9	30,819	28.2	1,086	26.0
30.0–34.9	14,336	13.1	492	11.8
35.0–39.9	6,199	5.7	223	5.3
40.0 and over	3,470	3.2	140	3.4
SEIFA Index of Disadvantage
1 (Most disadvantaged)	78,473	20.7	1,498	12.4	<0.01
2	62,969	16.6	1,528	12.7
3	83,153	22.0	2,620	21.7
4	87,116	23.0	3,093	25.7
5 (Least disadvantaged)	66,987	17.7	3,320	27.5
Remoteness
Major cities	244,632	64.2	8,778	72.6	<0.01
Inner regional	80,205	21.1	2,113	17.5
Outer regional	44,867	11.8	1,009	8.3
Remote	7,082	1.9	155	1.3
Very remote	4,252	1.1	41	0.3
Other^(b)	307		9
Smoking status during pregnancy ^(c)
Yes	47,179	19.4	321	3.8	<0.01
No	196,661	80.7	8,181	96.2
Parity
Primiparous	154,519	40.5	7,549	62.4	<0.01
Multiparous	226,826	59.5	4,556	37.6
Health insurance
Public	256,511	67.6	3,274	27.1	<0.01
Private	122,987	32.4	8,812	72.9
Other ^(d)	1,847		19

(a) Maternal pre-pregnancy body mass index (BMI) was available in only one jurisdiction between 2008 and 2009 (N = 119,257), accounting for 30.3% of the study population.
(b) Includes 289 non-Australian residents and 27 not stated cases.
(c) Smoking during pregnancy was indicated in two jurisdictions between 2007 and 2009, and one jurisdiction between 2008 and 2009 (N = 253,444), accounting for 64.42% of the study population.
(d) Includes 1,124 not applicable and 742 not stated cases.

ISSN: 1471-2393