Table 1.

Background characteristics of participants in a case control study of mastitis.

	Cases (N = 100) n (%)	Controls (N = 99) n (%)	Odds Ratio	95% CI		Significance*
Mother's age (mean, years)	33.5	31.7				**p = 0.004
Mother's education:
Completed secondary	89 (89)	90 (91)	1.24	0.49	3.13	p = 0.655
Completed tertiary degree	63 (63)	70 (71)	1.02	0.90	1.16	p = 0.779
Family income (n = 184)
up to $50,000	20/92 (22)	10/92 (11)
$50,001–70,000	29/92 (32)	17/92 (19)	0.85	0.32	2.24
more than $70,000	43/92 (47)	65/92 (71)	0.33	0.14	0.77	**p = 0.004
Mother paid work/study	7 (7)	6 (6)	1.20	0.50	2.86	p = 0.687
Private health insurance	51 (51)	78 (80)	0.27	0.14	0.50	**p = 0.000
Baby's age in days
(mean and range)	33.7 (6–728)	34 (13–77)				t-test ns
median	16	36
Multiple birth (twins)	3 (3)	3 (3)	0.99	0.19	5.03	p = 0.990
Primiparity	69 (69)	60 (61)	0.69	0.39	1.24	p = 0.216
Caesarean section	35 (35)	32 (32)	1.13	0.63	2.03	p = 0.690

(n = 100 women with mastitis and 99 breastfeeding controls). Melbourne, Australia, 2002–2004.

*chi-square test for all analyses, except t-test for mother's and baby's age.

**statistically significant.

ns = not significant.