Background
Methods
Study design and period
Sample size and sampling techniques
Outcome and treatment variables
Data management and analysis
Ethical considerations
Results
Descriptive characteristics of the study participants
Variables | Before matching | ||||
---|---|---|---|---|---|
NBI | Pct. | SBI | Pct. | p-value | |
Residence
| |||||
Urban | 14,401 | 63.33 | 8340 | 36.67 | < 0.001 |
Rural | 44,831 | 54.03 | 38,149 | 45.97 | |
Country
| |||||
Burundi, 2016-17 | 5558 | 52.31 | 5068 | 47.69 | < 0.01 |
Ethiopia, 2016 | 4268 | 50.48 | 4187 | 49.52 | |
Kenya, 2014 | 8767 | 54.43 | 7339 | 45.57 | |
Comoros, 2012 | 1126 | 46.66 | 1287 | 53.34 | |
Madagascar, 2021 | 4739 | 49.89 | 4760 | 50.11 | |
Malawi, 2015-16 | 9016 | 70.54 | 3766 | 29.46 | |
Mozambique, 2015 | 4894 | 57.29 | 3648 | 42.71 | |
Rwanda, 2019-20 | 3438 | 62.57 | 2057 | 37.43 | |
Tanzania, 2015-16 | 4054 | 51.94 | 3751 | 48.06 | |
Uganda, 2016 | 5622 | 46.29 | 6524 | 53.71 | |
Zambia, 2018 | 4611 | 62.11 | 2813 | 37.89 | |
Zimbabwe, 2015 | 3139 | 70.89 | 1289 | 29.11 | |
Mothers educational status
| |||||
No education | 15,351 | 50.37 | 15,125 | 49.63 | < 0.001 |
Primary | 31,448 | 56.34 | 24,367 | 43.66 | |
Secondary | 10,738 | 63.53 | 6164 | 36.47 | |
Higher | 1695 | 67.05 | 833 | 32.95 | |
Household wealth status
| |||||
Poorest | 14,443 | 48.71 | 15,205 | 51.29 | < 0.001 |
Poorer | 11,918 | 53.44 | 10,385 | 46.56 | |
Middle | 11,228 | 57.19 | 8406 | 42.81 | |
Richer | 10,933 | 60.36 | 7181 | 39.64 | |
Richest | 10,710 | 66.85 | 5312 | 33.15 | |
Sex of household head
| |||||
Male | 44,022 | 54.35 | 36,969 | 45.65 | 0.001 |
Female | 15,210 | 61.50 | 9520 | 38.50 | |
Marital status
| |||||
Not married | 16,023 | 58.22 | 11,497 | 41.78 | 0.01 |
Married | 43,209 | 55.25 | 34,992 | 44.75 | |
Number of births before the current birth
| |||||
1–3 | 27,933 | 57.22 | 20,880 | 42.78 | 0.001 |
> 3 | 31,299 | 55.00 | 25,609 | 45.00 | |
Maternal age (in years)
| |||||
15–24 | 7066 | 40.14 | 10,537 | 59.86 | < 0.001 |
25–34 | 32,682 | 56.73 | 24,927 | 43.27 | |
≥ 35 | 19,484 | 63.86 | 11,025 | 36.14 | |
Media exposure
| |||||
No | 21,296 | 53.13 | 18,788 | 46.87 | 0.001 |
Yes | 37,899 | 57.79 | 27,679 | 42.21 |
Estimations of propensity score
Variables | Short birth interval | |
---|---|---|
Coef. With 95% CI | P-value | |
Birth order | 0.47 (0.43, 0.49) | < 0.001 |
Media exposure | 0.03 (-0.003, 0.05) | 0.082 |
Marital status | 0.08 (0.05, 0.11) | < 0.001 |
Residence | 0.06 (0.03, 0.09) | < 0.001 |
Sex of household | -0.25 (-0.28,-0.21) | < 0.001 |
Household wealth status | -0.12 (-0.13, -0.11) | < 0.001 |
Maternal educational status | -0.13 (-0.15, -0.11) | < 0.001 |
Maternal education | -0.66 (0.68, 0.64) | < 0.001 |
Constant term | 0.80 (0.70, 0.90) | < 0.001 |
Number of observations | 105,662 | |
LR chi2(8) | 5567.88 | |
Prob > chi2 | < 0.0001 | |
Pseudo R2 | 0.0384 | |
Log likelihood | -69686.91 |
Impact of birth interval on under-five mortality
Impact of short birth interval on under-five mortality | Treated | Control | Difference | Standard error | t-statistic | p-value |
---|---|---|---|---|---|---|
Unmatched | 0.0606 | 0.0399 | 0.0207 | 0.0013 | 15.53 | |
ATT | 0.0609 | 0.0397 | 0.0212 | 0.0014 | 14.51 | < 0.05 |
ATU | 0.039 | 0.0606 | 0.0217 | |||
ATE | 0.0214 |
Quality of matching
Common support
Assigned treatment | Off support | On support | Total |
---|---|---|---|
Optimal birth interval | 2 | 59,193 | 59,195 |
Short birth interval | 0 | 46,467 | 46,467 |
Total | 2 | 105,660 | 105,662 |
Balancing test
Variable | Sample | Mean | % bias | % Bias reduction | t-statistic | p-value | |
---|---|---|---|---|---|---|---|
Treated | Control | ||||||
Residence | Unmatched | 0.82 | 0.76 | 15.7 | 25.12 | < 0.001 | |
Matched | 0.82 | 0.82 | -0.2 | 98.6 | -0.35 | 0.726 | |
Media exposure | Unmatched | 0.60 | 0.64 | -9.2 | -14.84 | < 0.001 | |
Matched | 0.60 | 0.60 | -0.0 | 99.8 | -0.03 | 0.979 | |
Marital status | Unmatched | 0.75 | 0.73 | 5.3 | 8.51 | < 0.001 | |
Matched | 0.75 | 0.75 | 0.0 | 99.3 | 0.06 | 0.952 | |
Sex of household head | Unmatched | 0.20 | 0.26 | -12.4 | -19.87 | < 0.001 | |
Matched | 0.20 | 0.20 | 0.1 | 99.2 | 0.15 | 0.877 | |
Birth order | Unmatched | 0.55 | 0.53 | 4.5 | 7.31 | < 0.001 | |
Matched | 0.55 | 0.55 | 0.0 | 99.3 | 0.05 | 0.963 | |
Household wealth status | Unmatched | 2.50 | 2.86 | -25.0 | -40.23 | < 0.001 | |
Matched | 2.50 | 2.50 | 0 | 99.8 | 0.07 | 0.947 | |
Maternal education status | Unmatched | 0.84 | 0.98 | -18.7 | -30.13 | < 0.001 | |
Matched | 0.84 | 0.84 | 0.2 | 99.1 | 0.26 | 0.796 | |
Maternal age | Unmatched | 1.01 | 1.21 | -30.2 | -48.97 | < 0.001 | |
Matched | 1.01 | 1.01 | -0.0 | 99.9 | -0.05 | 0.962 |
Standardized bias
Significance of the model
Sensitivity analysis
Gamma (Γ) | Test statistics | Significance level | ||
---|---|---|---|---|
Over-estimation (Q_mh+) | Under-estimation (Q_mh-) | Over-estimation (p_mh+) | Under-estimation (p_mh-) | |
1 | 1.40 | 1.40 | 0.08 | 0.08 |
1.05 | 1.17 | 1.63 | 0.12 | 0.05 |
1.1 | 0.95 | 1.85 | 0.17 | 0.03 |
1.15 | 0.74 | 2.06 | 0.23 | 0.02 |
1.2 | 0.55 | 2.26 | 0.29 | 0.01 |
1.25 | 0.36 | 2.46 | 0.36 | 0.007 |
1.3 | 0.17 | 2.65 | 0.43 | 0.004 |
1.35 | -0.003 | 2.83 | 0.50 | 0.002 |
1.4 | -0.042 | 3.01 | 0.52 | 0.001 |
1.45 | 0.12 | 3.18 | 0.45 | 0.0007 |
1.5 | 0.28 | 3.34 | 0.39 | 0.0004 |
1.55 | 0.43 | 3.50 | 0.33 | 0.0002 |
1.6 | 0.58 | 3.66 | 0.28 | 0.0001 |
1.65 | 0.72 | 3.82 | 0.24 | 0.00006 |
1.7 | 0.86 | 3.96 | 0.19 | 0.0003 |
1.75 | 0.99 | 4.11 | 0.15 | 0.00002 |
1.8 | 1.13 | 4.25 | 0.13 | 0.00001 |
1.85 | 1.25 | 4.39 | 0.104 | 0.00005 |
1.9 | 1.38 | 4.53 | 0.08 | 0.000003 |
1.95 | 1.50 | 4.66 | 0.07 | 0.000001 |
2.0 | 1.62 | 4.79 | 0.052 | 0.000008 |