Table 5. Hazard ratios (HR) and 95% confidence intervals (CI) for ethnic and sociocultural factors associated with under-five mortality, Nigeria 2008.

	Model 1	Model 2	Model 3	Model 4	Model 5
Variables	HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)
Ethnicity
Hausa/Fulani/Kanuri	1	1	1	1	1
Igbo	0.58 (0.55–0.61)***	0.91 (0.77–1.07)	1.00 (0.84–1.20)	0.97 (0.82–1.15)	1.12 (0.93–1.34)
Yoruba	0.39 (0.37–0.42)***	0.51 (0.42–.62)***	0.57 (0.47–0.70)***	0.55 (0.45–0.67)***	0.63 (0.52–0.78)***
Others	0.66 (0.64–0.68)***	0.87 (0.80–0.96)**	0.93 (0.84–1.03)	0.90 (0.82–0.99)*	0.98 (0.88–1.08)
Mother's age at first birth
<18		1	1	1	1
18+		0.94 (0.86–1.02)	0.95 (0.87–1.04)	0.86 (0.79–0.94)**	0.89 (0.81–0.97)**
Birth order
1		1	1	–	–
2–4		0.92 (0.89–0.96)	0.92 (0.89–0.96)	–	–
5+		1.78 (1.62–1.95)***	1.73 (1.58–1.90)***	–	–
Birth interval
<24		1	1	1	1
24+		0.54 (0.38–0.78)**	0.50 (0.34–0.73)***	0.55 (0.38–0.79)**	0.50 (0.34–0.74)***
Place of delivery
Home		1	1	1	1
Health facility		0.92 (0.82–1.03)	1.00 (0.89–1.12)	0.89 (0.79–0.98)*	1.00 (0.89–1.13)
Family structure
Monogamous		1	1	1	1
Polygynous		1.61 (1.46–1.77)***	1.57 (1.42–1.72)***	1.48 (1.35–1.64)***	1.42 (1.28–1.57)***
Parity
<3		–	–	1	1
3–4		–	–	0.47 (0.42–0.52)***	0.46 (0.41–0.51)***
5+		–	–	0.45 (0.40–0.51)***	0.43 (0.38–0.49)***
Mothers’ education
No education		–	1	–	1
Primary		–	0.98 (0.87–1.11)	–	1.02 (0.90–1.15)
Secondary or higher		–	0.79 (0.68–0.93)**	–	0.73 (0.62–0.85)***
Father's education
No education		–	1	–	1
Primary		–	0.94 (0.83–1.06)	–	0.91 (0.81–1.03)
Secondary or higher		–	0.89 (0.79–1.012)	–	0.85 (0.75–0.96)**

^* p < 0.05, **p < 0.01, ***p < 0.001.