Table 5.

Parity and 30-month incident KR.

			Crude	Age, BMI, race-Adj.		Multi-Adj.*
Number of Births	Total # Knees	# (%)With incident KR	RR	RR	p-value	RR	p-value
0	417	6 (1.44)	0.7 (0.2, 2.2)	0.7 (0.2, 2.3)	0.5540	0.9 (0.3, 2.9)	0.8580
1(ref)	358	7 (1.96)	1.0	1.0		1.0
2	1013	33 (3.26)	1.6 (0.7, 4.0)	1.8 (0.7, 4.5)	0.2398	2.0 (0.8, 5.1)	0.1624
3	732	38 (5.19)	2.6 (1.1, 6.4)	2.4 (1.0, 6.1)	0.0594	2.7 (1.1, 6.8)	0.0375
4	373	14 (3.75)	1.9 (0.7, 5.2)	1.7 (0.6, 4.8)	0.3199	1.8 (0.6, 5.3)	0.2590
5–12	298	17 (5.70)	2.8 (1.1, 7.5)	2.2 (0.8, 6.2)	0.1299	2.7 (1.0, 7.3)	0.0494
P for linear trend							0.0070

^*adjusted for age, BMI, race, education, occupation, WOMAC knee pain, pain medication, estrogen use, clinical site