Table 1.

Demographics and obstetric characteristics

	Case	Control	p Value
	N (%)	N (%)
Total	295 (100.0)	570 (100.0)
Country
Australia	227 (76.9)	436 (76.5)	0.88
New Zealand	68 (23.1)	134 (23.5)
Maternal age
<25	7 (2.4)	93 (16.3)	<0.001
25–29	44 (14.9)	147 (25.8)
30–34	94 (31.9)	177 (31.1)
35–39	112 (38.0)	121 (21.2)
≥40	38 (12.9)	32 (5.6)
Indigenous status (Australian only)
Yes	11 (4.8)	13 (3.0)	0.21
No	202 (89.0)	403 (92.4)
Not stated	14 (6.2)	20 (4.6)
Ethnicity (New Zealand only)
Maori	13 (19.1)	18 (13.4)	0.34
New Zealand European	34 (50.0)	63 (47.0)
Pacific peoples	5 (7.4)	17 (12.7)
Other	12 (17.6)	34 (25.4)
Not stated	4 (5.9)	2 (1.5)
Body mass index (kg/m2)
<25	115 (39.0)	272 (47.7)	<0.05
25–29.9	66 (22.4)	128 (22.5)
≥30	78 (26.4)	112 (19.6)
Not stated	36 (12.2)	58 (10.2)
Smoking during pregnancy
Yes	56 (19.0)	97 (17.0)	0.45
No	215 (72.9)	429 (75.3)
Not stated	24 (8.1)	44 (7.7)
Parity
0	46 (15.6)	240 (42.1)	<0.001
1–2	159 (53.9)	274 (48.1)
≥3	90 (30.5)	56 (9.8)
Number of previous caesarean deliveries
No prior caesarean delivery	43 (14.6)	225 (39.5)	<0.001
1	89 (30.2)	80 (14.0)
2	62 (21.0)	19 (3.3)
≥3	50 (16.9)	3 (0.5)
Not applicable (no prior births)	46 (15.6)	240 (42.1)
Not stated	5 (1.7)	3 (0.5)
Last pregnancy delivery by caesarean delivery
Yes	188 (63.7)	91 (16.0)	<0.001
No	55 (18.6)	234 (41.1)
Not applicable (no prior births)	46 (15.6)	240 (42.1)
Not stated	6 (2.0)	5 (0.9)
Placenta praevia during pregnancy
Yes	130 (44.1)	8 (1.4)	<0.001
No	165 (55.9)	562 (98.6)
Multiple pregnancy
Yes	15 (5.1)	13 (2.3)	<0.05
No	280 (94.9)	555 (97.4)
Not stated	0 (0.0)	2 (0.4)
Assisted conception
Yes	24 (8.1)	15 (2.6)	<0.001
No	259 (87.8)	521 (91.4)
Not stated	12 (4.1)	34 (6.0)