Table 2.

Multivariable model showing relative risk of preterm birth for women with RA and SLE by race/ethnicity

Comparison	Model	Preterm (< 37 vs. ≥ 37)		Interactiona
		SLE	RA	p-value
NH Black vs. NH White	RR	1.47 (1.16, 1.85)	2.22 (1.61, 3.05)	0.040
	aRR	1.33 (1.04, 1.71)	2.44 (1.73, 3.43)	0.035
NH Black vs. Hispanic	RR	1.07 (0.87, 1.32)	2.32 (1.69, 3.18)	< 0.001
	aRR	0.99 (0.75, 1.25)	2.31 (1.65, 3.23)	< 0.001
NH Black vs. Asian	RR	1.04 (0.81, 1.33)	1.60 (1.05, 2.46)	0.086
	aRR	0.90 (0.67 1.20)	1.99 (1.22, 3.24)	0.073
Hispanic vs. NH White	RR	1.37 (1.15, 1.63)	0.96 (0.75, 1.22)	0.019
	aRR	1.34 (1.10, 1.63)	1.06 (0.80, 1.40)	0.064
Hispanic vs. Asian	RR	0.97 (0.80, 1.18)	0.69 (0.48, 1.00)	0.112
	aRR	0.90 (0.72, 1.13)	0.86 (0.57, 1.30)	0.249
Asian vs. NH White	RR	1.41 (1.13, 1.76)	1.38 (0.95, 2.02)	0.933
	aRR	1.48 (1.16, 1.90)	1.23 (0.80, 1.88)	0.887

RR relative risk, aRR adjusted relative risk (adjusted for maternal age, pre-pregnancy body mass index (BMI), insurance, education, country of origin, parity, and smoking), RR relative risk, SLE systemic lupus erythematosus, RA rheumatoid arthritis, NH non-Hispanic

^aThe interaction p-value represents whether there was a statistically significant difference in the relative risks for the association between race/ethnicity and PTB in women with RA compared to women with SLE