Table VI.

Pairwise comparisons of relative risk of stratified preterm birth by maternal race, ethnicity, and nativity

		Extreme preterm birth	Moderate preterm birth	Late preterm birth
Reference groups	Comparison group	aRR (Bonferroni-corrected 95% CI)
US-born HW
	Foreign-born NHB	2.5 (1.67–3.76)	1.01 (0.78–1.30)	0.76 (0.66–0.88)
	Foreign-born NHW	0.81 (0.50–1.32)	0.75 (0.58–0.97)	0.69 (0.61–0.79)
	Foreign-born HW	0.48 (0.21–1.14)	0.43 (0.27–0.69)	0.74 (0.61–0.90)
US-born NHB
	Foreign-born NHB	0.92 (0.72–1.17)	0.71 (0.59–0.86)	0.69 (0.61–0.77)
	Foreign-born NHW	0.29 (0.21–0.43)	0.53 (0.44–0.65)	0.63 (0.57–0.70)
	Foreign-born HW	0.18 (0.08–0.39)	0.30 (0.19–0.47)	0.67 (0.56–0.80)
US-born HB
	Foreign-born NHB	1.07 (0.65–1.76)	0.72 (0.50–1.02)	0.79 (0.63–0.98)
	Foreign-born NHW	0.35 (0.20–0.61)	0.53 (0.37–0.76)	0.72 (0.58–0.89)
	Foreign-born HW	0.20 (0.08–0.51)	0.31 (0.18–0.52)	0.76 (0.59–0.99)

Model adjusted for maternal age, marital status, insurance, education, tobacco use, medical comorbidities, and infant birth year. These estimates were derived from postestimation linear comparisons and Bonferroni adjusted for multiple comparisons. Significant aRRs are shown in bold.