Table 3.

Results of generalized additive models of hospital-based childbirth by country

	Kenya			Malawi			Nigeria			Tanzania
Approximate significance of smooth terms	EDF	REF DF	p-value	EDF	REF DF	p-value	EDF	REF DF	p-value	EDF	REF DF	p-value
Wealth index × travel time ($\sqrt[3]{\text{hours}}$)	6.48	7.31	< 0.001	10.71	24.00	< 0.001	11.77	24.00	< 0.001	8.37	24.00	< 0.001
Maternal age at birth (years)	2.36	2.96	< 0.001	2.89	9.00	< 0.001	2.54	9.00	< 0.001	3.79	6.00	< 0.001
Parametric coefficients of linear terms	EST	SE	p-value	EST	SE	p-value	EST	SE	p-value	EST	SE	p-value
Maternal education (years)	0.06	0.01	< 0.001	0.03	0.01	< 0.001	0.09	0.00	< 0.001	−0.05	0.01	< 0.001
Birth order	− 0.28	0.02	< 0.001	− 0.12	0.02	< 0.001	−0.10	0.01	< 0.001	−0.16	0.03	< 0.001
Random effects	EDF	REF DF	p-value	EDF	REF DF	p-value	EDF	REF DF	p-value	EDF	REF DF	p-value
Survey cluster	515	1052	< 0.001	482	609	< 0.001	575	701	< 0.001	319	481	< 0.001
Mean of predicted probability of hospital birth (%)	33.2			32.7			26.6			29.6

EST Estimate, SD Standard error, EDF Estimated degrees of freedom, REF DF Reference degrees of freedom