Characteristics of the study participants
Table 1 shows the background characteristics of the children, their parents, and the countries from which the children were chosen. In all, 38361 observations were available from 4 countries. Of these observations, 9378, 9632, 9641, and 9710 were conducted in Ethiopia, India, Peru, and Vietnam, respectively. The percentage of observations (children chosen) from each country was nearly identical, the minimum was 9378(24.45%) from Ethiopia and the maximum was 9710(25.31%) from Vietnam (Fig. 1). The majority of the children in the sample were from rural areas, and more than half of them were males. In 2002, the majority of children's mothers (40.3%) were uneducated. However, the percentage of uneducated mothers has decreased over time from 40.3% in 2002 to 24.6% in 2016. Similarly, the percentage of uneducated fathers fell from 32.6% in 2002 to 12.6% in 2016 (Table 1).
Table 1
Background Characteristics of children in Ethiopia, India, Peru, and Vietnam from 2002 to 2016
Characteristics | Year of survey |
2002 | 2006 | 2009 | 2013 | 2016 |
Child's sex | Male | n | 4091 | 4040 | 3990 | 3935 | 3900 |
% | 51.8 | 52.1 | 52.0 | 52.1 | 52.1 |
Female | n | 3814 | 3711 | 3682 | 3619 | 3579 |
% | 48.2 | 47.9 | 48.0 | 47.9 | 47.9 |
Area of residence | Urban | n | 2976 | 2925 | 2940 | 3015 | 3044 |
% | 37.6 | 37.7 | 38.3 | 39.9 | 40.7 |
Rural | n | 4929 | 4826 | 4715 | 4539 | 4434 |
% | 62.4 | 62.3 | 61.5 | 60.1 | 59.3 |
Access to safe drinking water | No | n | 3999 | 3340 | 2771 | 2569 | 2198 |
% | 50.6 | 43.1 | 36.2 | 34.0 | 29.5 |
Yes | n | 3901 | 4411 | 4892 | 4981 | 5257 |
% | 49.4 | 56.9 | 63.8 | 66.0 | 70.5 |
Father's education level | Uneducated | n | 2295 | 1464 | 1232 | 870 | 809 |
% | 32.6 | 21.0 | 18.4 | 13.2 | 12.6 |
Primary school | n | 2462 | 3013 | 2998 | 3010 | 2713 |
% | 34.9 | 43.2 | 44.7 | 45.8 | 42.3 |
Secondary school | n | 1749 | 1765 | 1734 | 1750 | 1849 |
% | 24.8 | 25.3 | 25.9 | 26.6 | 28.8 |
Diploma and above | n | 521 | 553 | 547 | 617 | 676 |
% | 7.4 | 7.9 | 8.2 | 9.4 | 10.5 |
Adult and Religious education | n | 21 | 176 | 189 | 324 | 364 |
% | 0.3 | 2.5 | 2.8 | 4.9 | 5.7 |
Mother's education level | Uneducated | n | 3115 | 2357 | 2004 | 1844 | 1757 |
% | 40.3 | 31.1 | 27.2 | 25.4 | 24.6 |
Primary school | n | 2660 | 3113 | 3212 | 3133 | 2924 |
% | 34.4 | 41.1 | 43.6 | 43.1 | 41.0 |
Secondary school | n | 1522 | 1524 | 1510 | 1538 | 1628 |
% | 19.7 | 20.1 | 20.5 | 21.2 | 22.8 |
Diploma and above | n | 414 | 412 | 432 | 462 | 525 |
% | 5.4 | 5.4 | 5.9 | 6.4 | 7.4 |
Adult and Religious education | n | 19 | 163 | 215 | 287 | 300 |
% | 0.2 | 2.2 | 2.9 | 4.0 | 4.2 |
The four Low- and middle-income countries | Ethiopia | n | 1917 | 1908 | 1877 | 1871 | 1805 |
% | 24.3 | 24.6 | 24.5 | 24.8 | 24.1 |
India | n | 1970 | 1937 | 1924 | 1907 | 1894 |
% | 24.9 | 25.0 | 25.1 | 25.2 | 25.3 |
Peru | n | 2035 | 1950 | 1937 | 1876 | 1843 |
% | 25.7 | 25.2 | 25.2 | 24.8 | 24.6 |
Vietnam | n | 1983 | 1956 | 1934 | 1900 | 1937 |
% | 25.1 | 25.2 | 25.2 | 25.2 | 25.9 |
Figure 2 depicts the graphical exploration of the characteristics of numeric variables such as father's age, mother's age, wealth index, and household size. From Fig. 2, it can be seen that Vietnam had the highest wealth index and the lowest household size throughout all the study periods. In contrast, Ethiopia had the lowest wealth index and the largest household size from 2002 and 2016. In all study periods from 2002 to 2016, the parents (father and mother) of Indian children had the lowest average ages, while the parents of Ethiopian children had the highest average ages.
Height-for-age
From 2002 to 2016, height-for-age z-score (HAZ) values were computed for each child in four study countries to assess the trends and prevalence of stunting. Figure 3 shows trends in the mean HAZ of children in the four study countries. The minimum (-1.72) and maximum (-0.98) estimated mean HAZ were recorded in Ethiopian males and females, respectively. Children in Vietnam had approximately the highest mean HAZ in both genders, except in 2016, where Ethiopian females had the highest estimated mean HAZ (-0.89).
Between-country Patterns Of Stunting Prevalence From 2002 To 2016
The within- and between-country status of stunting prevalence was presented in Table 2 and Fig. 4, respectively. From the visual inspection of the between-country trends of stunting prevalence displayed in Fig. 4, the trends of stunting in children from 2002 to 2016 have declined from an estimated 30% in 2002 to 20% in 2016. In fact, the four countries have observed reductions in stunting prevalence. However, the greatest decline occurred in Vietnam to 2.6% in moderately stunted and to 0.5% in severely stunted (Fig. 6).
From the results of within-county prevalence of stunting status presented in Table 2, for all four countries, the highest prevalence of severe stunting was observed in 2002 and moderate stunting was observed in 2006. For instance, the prevalence of severe stunting in 2002 was 20.9%, 10.8%, 9.1%, and 5.7% in Ethiopia 23, India, Peru, and Vietnam, respectively. On the other hand, the highest prevalence of moderate stunting observed in 2006 was 23.2%, 28.7%, 24.5%, and 20.4% in Ethiopia, India, Peru, and Vietnam, respectively (Table 2). Accordingly, the lowest prevalence of severe stunting was observed in 2009 for both Ethiopia and India (5.7% and 5.5%, respectively) and in 2016 for Peru and Vietnam (both 2%).
Table 2
Within-country (Ethiopia, India, Peru, and Vietnam) prevalence of stunting status from 2002 to 2016
Country | Stunting | Prevalence, n(%) |
2002 | 2006 | 2009 | 2013 | 2016 |
Ethiopia | Not stunted | n | 1112 | 1310 | 1474 | 1329 | 1345 |
% | 58 | 68.7 | 78.5 | 71 | 74.5 |
Moderately stunted | n | 405 | 442 | 296 | 431 | 324 |
% | 21.1 | 23.2 | 15.8 | 23 | 18 |
Severely stunted | n | 400 | 156 | 107 | 111 | 136 |
% | 20.9 | 8.2 | 5.7 | 5.9 | 7.5 |
India | Not stunted | n | 1365 | 1246 | 1368 | 1350 | 1368 |
% | 69.3 | 64.3 | 71.1 | 70.8 | 72.2 |
Moderately stunted | n | 392 | 556 | 450 | 444 | 415 |
% | 19.9 | 28.7 | 23.4 | 23.3 | 21.9 |
Severely stunted | n | 213 | 135 | 106 | 113 | 111 |
% | 10.8 | 7 | 5.5 | 5.9 | 5.9 |
Peru | Not stunted | n | 1458 | 1303 | 1537 | 1520 | 1547 |
% | 71.6 | 66.8 | 79.3 | 81 | 83.9 |
Moderately stunted | n | 392 | 478 | 317 | 289 | 259 |
% | 19.3 | 24.5 | 16.4 | 15.4 | 14.1 |
Severely stunted | n | 185 | 169 | 83 | 67 | 37 |
% | 9.1 | 8.7 | 4.3 | 3.6 | 2 |
Vietnam | Not stunted | n | 1570 | 1461 | 1547 | 1528 | 1700 |
% | 79.2% | 74.7 | 80 | 80.4 | 87.8 |
Moderately stunted | n | 300 | 399 | 326 | 288 | 198 |
% | 15.1 | 20.4 | 16.9 | 15.2 | 10.2 |
Severely stunted | n | 113 | 96 | 61 | 84 | 39 |
% | 5.7 | 4.9 | 3.2 | 4.4 | 2 |
Figures 5 and 6 depict the prevalence and patterns of stunting status from 2002 to 2016. The percentages of between-country prevalence were derived using the sum of children numbers affected in each country divided by the total children in four countries. The percentages of within-country prevalence, on the other hand, were calculated by dividing the total number of children exposed in each country by the total number of children in the corresponding country.
Results of Generalized linear mixed-effects model
Stunting determinants were chosen by first including all considered factors into the model and then evaluating their significance. Subsequently, those factors that were statistically significant in determining a child stunting were considered and interpreted. In this regard, factors such as a child’s country, a child’s age, household size, wealth index, child’s sex, residence area, father's education level, and mother's education level were statistically significant determinants of stunting. However, father's age and mother's age were not statistically significant determinants of stunting. The significance tests of variables are presented in Table 3.
Table 3
The fixed effects significance tests in determinants of stunting
Effect | Num DF | Den DF | F Value | Pr > F |
Country | 3 | 32616 | 30.64 | < .0001 |
Child's age | 4 | 32616 | 46.21 | < .0001 |
Mother’s age | 2 | 32616 | 0.72 | 0.4859 |
Father’s age | 2 | 32616 | 0.07 | 0.9349 |
Household size | 1 | 32616 | 8.59 | 0.0034 |
Wealth index | 2 | 32616 | 52.11 | < .0001 |
Child's sex | 1 | 32616 | 36.00 | < .0001 |
Residence area | 1 | 32616 | 50.83 | < .0001 |
Father’s education level | 4 | 32616 | 11.59 | < .0001 |
Mother’s education level | 4 | 32616 | 25.16 | < .0001 |
Table 4 depicts the estimated odds ratios of factors related to parents’ and children’s characteristics in determining a child’s stunting. The findings of the study revealed that there were disparities in stunting prevalence in four low- and middle-income countries; Ethiopia, India, Peru, and Vietnam. Compared to children in Vietnam, children in Ethiopia, India, and Peru were more stunted (Ethiopia: OR = 1.53, 95% CI: 1.21–1.93, p = 0.0003, India: OR = 2.33, 95% CI: 1.89–2.88, p < 0.0001, Peru: OR = 2.57, 95% CI: 2.04–3.24, p < 0.0001). In terms of ages, children were more stunted at five years old (OR = 1.27, 95% CI: 1.14–1.42, p < 0.0001) and less stunted at eight (OR = 0.61, 95% CI: 0.53–0.69, p < 0.0001), twelve (OR = 0.76, 95% CI: 0.65–0.89, p = 0.0006), and fifteen (OR = 0.55, 95% CI: 0.46–0.66, p < 0.0001) years old.
Girls and boys are not equally likely to be stunted in these four low- and middle-income countries, but in these countries, stunting afflicts fewer girls (OR = 0.65, 95% CI: 0.56–0.75, p < 0.0001) than boys. This suggests that girls had a 35% lesser odds of stunting compared to boys. Children in rural households were more than 1.82 times (OR = 1.82, 95% CI: 1.54–2.15, p < 0.0001) as likely to be stunted as children in urban households.
Regarding parents-related factors, children from educated parents (mother and father), children from high wealth index households, and children from low household sizes were associated with lower odds of stunting. For instance, children born to mothers with a primary school, secondary school, and diploma and above education level had 0.72 (95% CI: 0.62–0.84, p < 0.0001), 0.35 (95% CI: 0.28–0.4, p < 0.0001), and 0.17 (95% CI: 0.11–0.27, p < 0.0001) times less likely to be stunted than children from uneducated mothers, respectively. Similarly, children born to fathers with a secondary school, and diploma and above education level had 0.53 (95% CI: 0.43–0.66, p < 0.0001), 0.499 (95% CI: 0.357–0.699, p < 0.0001), and 0.17 (95% CI: 0.11–0.27) times less likely to be stunted than children from uneducated mothers, respectively. Children from the medium and high wealth index households were less than 0.68 (95% CI: 0.61–0.76, p < 0.0001) and 0.43 (95% CI: 0.36–0.50, p < 0.0001) times as likely to be stunted as children from the low wealth index households, respectively.
Table 4
The fixed effects factors related to parents’ and children’s characteristics
Effect | Estimate | SE | OR | 95% CI | P-value |
Country (ref. = Vietnam) |
Ethiopia | 0.4261 | 0.1183 | 1.531 | 1.214–1.931 | 0.0003 |
India | 0.8468 | 0.1069 | 2.332 | 1.891–2.876 | < .0001 |
Peru | 0.9445 | 0.1181 | 2.572 | 2.04–3.241 | < .0001 |
Child's age in year (ref. = age one) |
Age five | 0.2384 | 0.0554 | 1.269 | 1.139–1.415 | < .0001 |
Age eight | -0.503 | 0.0661 | 0.605 | 0.531–0.688 | < .0001 |
Age twelve | -0.276 | 0.0799 | 0.759 | 0.649–0.887 | 0.0006 |
Age fifteen | -0.591 | 0.0915 | 0.554 | 0.463–0.663 | < .0001 |
Mother’s age in year (ref. = \(\le 29\) age) |
\(30\le age \le 36\) | 0.07984 | 0.0665 | 1.083 | 0.951–1.234 | 0.2301 |
\(\ge 37\) age | 0.09663 | 0.1016 | 1.101 | 0.903–1.344 | 0.3413 |
Father’s age in year (ref. = \(\le 34\) age) |
\(35\le age \le 41\) | 0.00028 | 0.0654 | 1 | 0.88–1.137 | 0.9966 |
\(>41\) age | 0.02459 | 0.0969 | 1.025 | 0.848–1.239 | 0.7996 |
Household size in number (\({r}{e}{f}. = \le 5 {h}{o}{u}{s}{e}{h}{o}{l}{d} {s}{i}{z}{e}\)) |
\(>5\) household size | 0.1478 | 0.0504 | 1.159 | 1.05–1.28 | 0.0034 |
Wealth index (ref. = low) |
Medium | -0.3833 | 0.0575 | 0.682 | 0.609–0.763 | < .0001 |
High | -0.8559 | 0.0839 | 0.425 | 0.36–0.501 | < .0001 |
Child's sex (ref. = Boy) |
Girl | -0.4372 | 0.0729 | 0.646 | 0.56–0.745 | < .0001 |
Residence area (ref. = Urban) |
Rural | 0.5994 | 0.0841 | 1.821 | 1.544–2.147 | < .0001 |
Father education level (ref. = uneducated) |
Adult and religious education | 0.1172 | 0.1465 | 1.124 | 0.844–1.498 | 0.4235 |
Primary school | -0.0896 | 0.0781 | 0.914 | 0.785–1.065 | 0.2512 |
Secondary school | -0.6365 | 0.1092 | 0.529 | 0.427–0.655 | < .0001 |
Diploma and above | -0.6942 | 0.1718 | 0.499 | 0.357–0.699 | < .0001 |
Mother education level (ref. = uneducated) |
Adult and religious education | -0.0921 | 0.1661 | 0.912 | 0.659–1.263 | 0.5793 |
Primary school | -0.3241 | 0.0784 | 0.723 | 0.62–0.843 | < .0001 |
Secondary school | -1.0428 | 0.1206 | 0.352 | 0.278-0.4 | < .0001 |
Diploma and above | -1.75 | 0.2174 | 0.174 | 0.113–0.266 | < .0001 |