Table 4.

Impact of the free maternal healthcare policy on infant mortality: Kernel-based propensity score matching with the difference in differences analysis using modified Poisson with robust SE

	Sensitivity analysis based on different model specification
	Modified Poisson model: clustering, weighting and stratification were adjusted		Cox-proportional hazard model: clustering, weighting and stratification were adjusted	Logistic regression model: clustering, weighting and stratification were adjusted	Probit regression model: clustering, weighting and stratification were adjusted	Modified Poisson model: clustering, weighting and stratification were adjusted
	No Kernel matching with PSM	With Kernel matching with PSM	With Kernel matching PSM	With Kernel matching with PSM	With Kernel matching with PSM	ATET weighting using PSM-IPTW	ATE weighting using PSM
	aRR (95% CI)	aRR (95% CI)	aHR (95% CI)	aOR (95% CI)	β (95% CI)	aRR (95% CI)	aRR (95% CI)
Time
Baseline: 2008	ref	ref	ref	ref	ref	ref	ref
End-line: 2014	0.79*** (0.73 to 0.86)	0.62*** (0.48 to 0.8)	0.62*** (0.49 to 0.78)	0.45*** (0.35 to 0.58)	−0.45*** (−0.59 to 0.32)	0.64*** (0.53 to 0.78)	0.77** (0.64 to 0.91)
Intervention
No FMHCP	ref	ref	ref	ref	ref	ref	ref
FMHCP	0.72*** (0.62 to 0.84)	0.87 (0.74 to 1.03)	0.89 (0.77 to 1.04)	0.86 (0.72 to 1.02)	−0.09 (−0.19 to 0.01)	0.84* (0.74 to 0.96)	0.83*** (0.76 to 0.92)
Time*FMHCP	0.49*** (0.39 to 0.61)	0.46*** (0.36 to 0.59)	0.45*** (0.35 to 0.57)	0.43*** (0.33 to 0.56)	−0.49*** (−0.64 to 0.34)	0.48*** (0.37 to 0.6)	0.55** (0.39 to 0.77)
Sex of household head
Male	ref	ref	ref	ref	ref	ref	ref
Female	0.88* (0.78 to 0.98)	0.75** (0.61 to 0.92)	0.81* (0.68 to 0.98)	0.96 (0.79 to 1.17)	−0.02 (−0.13 to 0.09)	0.87 (0.74 to 1.02)	0.88 (0.75 to 1.02)
Mothers’ current age
<18 years	ref	ref	ref	ref	ref	ref	ref
18–34 years	0.49*** (0.41 to 0.58)	0.49*** (0.37 to 0.66)	0.86 (0.65 to 1.14)	3.1*** (2.2 to 4.38)	0.63*** (0.44 to 0.81)	0.49*** (0.38 to 0.63)	0.59*** (0.46 to 0.75)
35+	0.49*** (0.4 to 0.59)	0.47*** (0.33 to 0.66)	0.95 (0.69 to 1.31)	5.74*** (3.92 to 8.4)	0.96*** (0.75 to 1.17)	0.46*** (0.35 to 0.61)	0.52*** (0.39 to 0.68)
Place of residence
Urban	ref	ref	ref	ref	ref	ref	ref
Rural	1.16** (1.05 to 1.29)	1.2 (0.96 to 1.5)	1.19 (0.97 to 1.46)	1.18 (0.96 to 1.45)	0.09 (−0.03 to 0.2)	1.14 (0.96 to 1.36)	1.13 (0.89 to 1.45)
Wealth quintile
Poorest	ref	ref	ref	ref	ref	ref	ref
Poorer	1.02 (0.92 to 1.12)	1.01 (0.87 to 1.17)	1 (0.87 to 1.15)	0.97 (0.81 to 1.16)	−0.02 (−0.12 to 0.08)	1.04 (0.91 to 1.18)	0.99 (0.86 to 1.15)
Middle	0.88* (0.79 to 0.98)	0.92 (0.77 to 1.11)	0.95 (0.8 to 1.12)	0.99 (0.8 to 1.23)	−0.01 (−0.13 to 0.11)	0.92 (0.79 to 1.07)	0.93 (0.78 to 1.11)
Richer	0.86* (0.75 to 0.99)	0.91 (0.7 to 1.19)	0.95 (0.74 to 1.21)	0.93 (0.68 to 1.28)	−0.03 (−0.2 to 0.14)	0.89 (0.72 to 1.09)	0.8* (0.64 to 1)
Richest	0.69*** (0.57 to 0.82)	0.78 (0.54 to 1.12)	0.81 (0.58 to 1.13)	0.8 (0.57 to 1.11)	−0.14 (−0.32 to 0.05)	0.68** (0.52 to 0.89)	0.73 (0.5 to 1.06)
Household size
1–4	ref	ref	ref	ref	ref	ref	ref
5–7	0.43*** (0.39 to 0.47)	0.45*** (0.38 to 0.52)	0.52*** (0.45 to 0.59)	0.54*** (0.45 to 0.65)	−0.34*** (−0.44 to 0.24)	0.46*** (0.4 to 0.52)	0.43*** (0.37 to 0.5)
8+	0.35*** (0.32 to 0.39)	0.4*** (0.34 to 0.48)	0.46*** (0.39 to 0.54)	0.43*** (0.35 to 0.52)	−0.45*** (−0.55 to 0.34)	0.42*** (0.36 to 0.49)	0.38*** (0.33 to 0.45)
Access to improved water
Improved	ref	ref	ref	ref	ref	ref	ref
Unimproved	1.05 (0.96 to 1.16)	1.03 (0.89 to 1.19)	1.02 (0.89 to 1.17)	1.02 (0.88 to 1.17)	0 (−0.07 to 0.08)	0.99 (0.86 to 1.15)	1.05 (0.9 to 1.22)
Access to an improved toilet facility
Improved, not shared	ref	ref	ref	ref	ref	ref	ref
Improved, shared	0.87* (0.78 to 0.97)	0.94 (0.79 to 1.1)	0.94 (0.81 to 1.09)	0.82* (0.69 to 0.97)	−0.11* (−0.2 to 0.01)	0.97 (0.83 to 1.13)	0.94 (0.78 to 1.13)
Unimproved	0.88** (0.81 to 0.96)	0.92 (0.8 to 1.05)	0.93 (0.82 to 1.05)	0.88 (0.75 to 1.02)	−0.07 (−0.15 to 0.02)	0.93 (0.82 to 1.05)	0.92 (0.79 to 1.06)
Mothers’ education
None	ref	ref	ref	ref	ref	ref	ref
Primary	0.9* (0.82 to 0.99)	0.82* (0.7 to 0.97)	0.82** (0.71 to 0.95)	0.69*** (0.58 to 0.83)	−0.21*** (−0.31 to 0.11)	0.81** (0.71 to 0.93)	0.89 (0.76 to 1.03)
JHS	0.88* (0.78 to 0.98)	0.83 (0.67 to 1.02)	0.77** (0.64 to 0.94)	0.54*** (0.43 to 0.67)	−0.35*** (−0.47 to 0.24)	0.82* (0.69 to 0.97)	0.87 (0.73 to 1.03)
Secondary or higher	0.7** (0.56 to 0.89)	0.78 (0.53 to 1.17)	0.71 (0.48 to 1.04)	0.38*** (0.24 to 0.58)	−0.55*** (−0.78 to 0.31)	0.78 (0.53 to 1.14)	0.69 (0.43 to 1.11)
Birth order
1st birth	ref	ref	ref	ref	ref	ref	ref
2nd birth	1.03 (0.93 to 1.15)	0.86 (0.72 to 1.03)	0.77** (0.65 to 0.91)	0.6*** (0.5 to 0.73)	−0.27*** (−0.38 to 0.17)	0.94 (0.82 to 1.08)	0.84* (0.71 to 1)
3rd birth	1.2** (1.05 to 1.37)	1.13 (0.91 to 1.4)	0.96 (0.79 to 1.17)	0.65*** (0.52 to 0.81)	−0.24*** (−0.36 to 0.12)	1.19 (1 to 1.43)	1.08 (0.88 to 1.34)
4th birth	1.59*** (1.42 to 1.79)	1.63*** (1.34 to 1.98)	1.25* (1.05 to 1.5)	0.7** (0.56 to 0.86)	−0.2** (−0.32 to 0.08)	1.66*** (1.42 to 1.93)	1.51*** (1.23 to 1.86)
Multiple births
Single	ref	ref	ref	ref	ref	ref	ref
Multiple	4.37*** (3.86 to 4.95)	3.95*** (3.16 to 4.95)	3.57*** (2.96 to 4.3)	3.59*** (2.75 to 4.67)	0.72*** (0.57 to 0.87)	4.24*** (3.58 to 5.03)	4.43*** (3.71 to 5.29)
Household ownership of bednet
No bednet	ref	ref	ref	ref	ref	ref	ref
Bednet	1.06 (0.98 to 1.14)	0.98 (0.88 to 1.09)	0.97 (0.88 to 1.08)	0.99 (0.88 to 1.12)	−0.01 (−0.08 to 0.06)	0.96 (0.86 to 1.06)	0.94 (0.85 to 1.05)
Country fixed effect	Adjusted	Adjusted	Adjusted	Adjusted	Adjusted	Adjusted	Adjusted

P value notations: ***p<0.001, **p<0.01, *p<0.05.

aHR, adjusted hazard ratio; aOR, adjusted odds ratio; aRR, adjusted relative risk; ATE, average treatment effect; ATET, average treatment effect on the treated; FMHCP, free maternal healthcare policy; IPTW, inverse probability of treatment weighting; PS, propensity scores.