The objective of this study was to present data on stunting prevalence according to socio-demographics and geographical circumstances from 2001 to 2016. When comparing the Nepal’s prevalence of stunting with India and Pakistan, whose per capita income are higher than Nepal, the prevalence of stunting in Nepal is lesser than both more developed South Asian countries by 12.2% for India in 2016  and by 3.8% for Pakistan in 2012 . On one hand, Nepal made impressive progress in reducing the prevalence of stunting with 21.4% reduction in 15 years, from 57.2% in 2001 to 35.8% in 2016. The reduction might be explained by upliftment in educational status of mothers, increase in access to health care, improvement in sanitation and implementation of integrated interventions [17,18,19,20]. The government doubled its investment in education from 10% in 1988/1992 to 20% in 2006/2011 leading to improvement in overall educational status including of mothers . Aligning with increasing budget in education, several reformative activities were done in bringing about the positive changes in education such as implementation of Welcome to School Program that started in 2005 focusing on enrolment for girls and disadvantaged groups, and National Literacy Campaign launched in 2008 for both children and adult education . The campaign was successful in lifting up the literacy of women aged 15–24 years close to the level of national average . Alongside, the Comprehensive Peace Agreement made in November 2006 between the government and the Communist Party of Nepal-Maoist brought steadiness in operation of school activity that was missing during the period of armed conflict . The provision of midday meals, separate toilets for girls and boys, free textbooks, residential schools for girls, and the presence of female teachers might have provided enabling environment for students, especially girls to continue going school . Additionally, scholarships were provided to all girls student from 2010/11 onwards, which otherwise were only provided to 50% of enrolled girls . The above mentioned interventions raised the literacy level of girls and women, who are apparently the future mothers. However, it was also noted that only 79.5% of the poorest quintile 15–24 years were literate compared to 98% from the richest quintile , which is similar to the result of this study. Similarly, the improvement in access to health sector was made by increasing budget in primary health care [19, 20] and by increasing the number of primary health care outreach clinics that provided grassroots health services, leading to significant improvements in immunizations, vitamin A supplementation, prenatal, neonatal and postnatal care (including nutritional advice), and treatment of common diseases, particularly diarrhoea, malaria, and acute respiratory infections . Further to this, improvement in sanitation was also noted with notable reduction in open defecation, from 36 to 10% from 2011 to 2016 [5, 11]. The construction of low-cost toilet facilities through Community-Led Total Sanitation intervention not only decreased open defecation rates but also brought changes in behaviour of community people to follow hygienic sanitation practices . Following the recommendation of Nepal Nutrition Assessment and Gap Analysis to roll out the nutrition specific and sensitive intervention, Nepal implemented a 5 year plan known as Multi-sectoral Nutrition Plan in 2012, which was endorsed by Government of Nepal in collaboration with development partners to reduce the burden of undernutrition in the country . This plan targets to reduce undernutrition among the first thousand days lives, adolescent girls, pregnant and lactating women among the poorer groups of the community through integrated intervention. Nutritional interventions are combined with water, sanitation, hygiene, social protection, and agricultural interventions to break the strong intergenerational cycle of stunting. Similarly, in 2011, Nepal participated in a global movement called Scaling Up Nutrition, which unites national leaders, civil society, bilateral and multilateral organizations, donors, businesses, and researchers in a collective effort to improve nutrition . On the other hand, based on the given current trend (i.e. 1.42% per annum), this rate of decline in stunting is not likely to move Nepal in the path to meet the WHO target of 40% fewer stunted children by 2025 . However, a 3.9% annual reduction is required to achieve this global target . The current prevalence of stunting (35.8%) is still very high. The challenges such as 8 % of the under five children suffering from diarrhoea and 20.9% of the rural households without toilets still remains to be tackled to minimize the prevalence .
Previous studies have found urban children taller than rural . Of particular relevance is a study from Paciorek, Stevens et al. (2013) that analysed 141 low and middle income countries between 1985 and 2011 showing urban children are taller and heavier than their rural counterparts from the majority of countries analysed . This contradicts the result of the present study. In the unadjusted analysis, the children living in the rural areas were associated with increased odds of stunting compared to their urban counterparts; however, in the adjusted analysis, no association was noted for all the survey years.
An analysis of three Cambodian Demographic Health Surveys found a significant relationship between stunting and mothers education , which is in accordance with the finding of this study. Rabbani, Khan et al. (2016) confirmed that mother’s education level and physical stature are statistically significant determinants for stunting . Similarly, this study found that children born to mothers with primary and secondary education have lower odds of getting stunted than those who are born to mothers with no education. This may be due to higher literacy level allowing mothers to follow good practices on maternal and child health care, infant and young child feeding practices, sanitation and hygiene, which ultimately affects the nutritional status of children . Incase of mothers without education, the prevalence of stunting decreased from 62 to 46% from 2001 to 2016. This reduction may be associated with the reduction in the overall proportion of mothers without education from 72 to 34% as noted in NDHS 2001 and 2016 respectively .
A large proportion of stunted children belong to the mid-western region. The mid-western development region of Nepal is the least developed region. For instance, the mid-western development region is the poorest region with the greatest difference between revenue and expenditures (− 7903.82 Nepalese Rupee) in comparison to nation’s richest region i.e. central development region generating 79.5% of the government revenue . Similarly, the central region’s per capita income was $1597, which was more than the national average of $1310 and the mid-western region had the lowest per capita income of $988 . The mid western development region has poor access to good health services; inadequate health facilities; a higher rate of male migration; low status of women within family groups leading to higher workload for females  and also lacks infrastructures such as roads, schools, hospitals, electricity, drinking water and irrigation, which has exacerbated social exclusion and increased livelihood insecurity . Additionally, the inequalities in the mid-western region is associated with widespread poverty and geographical isolation .
The decline in prevalence of stunting among children has been similar for the three ecological regions till 2011. After 2011, it was noticed that the prevalence of stunting in the terai region declined by less than 1 % from 2011 to 2016. The low reduction in stunting in the terai region from 2011 to 2016 might be due to a larger population in terai region deprived of basic education and health related facilities . In addition, this region holds ethnic populations who are socially, culturally and economically excluded from mainstream development and experience challenges to enjoy health, education and access to resources .
This study found that children born to poorest and poorer groups have higher odds of getting stunted than those born to richer groups. Similarly, the prevalence of stunting decreased by 18.4% from 2001 to 2016 for the poorest quintile and for the richest quintile, the reduction was by 25.6%. Additionally, the gap in prevalence of stunting between poorest and richest quintile was 25.5% in 2001, which increased to 32.7% in 2016. The reduction is not uniform among economic subgroups across the survey years, especially among lower socio-economic classes. This findings corresponds to the study done in Ghana using DHS data, which found that children belonging to the poorest households were more than twice at risk of being undernourished compared to their counterparts in the richest households . It is widely accepted that when economies grow and poverty is reduced, child nutrition improves owing to greater access to food, improved maternal and child care and better public health services . Alongside, instead of using blanket approach for delivering nutrition interventions, special emphasis should be given to vulnerable groups such as children belonging to poorest and poorer wealth quintile and to those born to mothers without education to balance the inequalities prevalent across different regions and subgroups by specifically bringing those behind within the reach of nutrition interventions.
The limitation of this study is that it has not given province level information on stunting, which is highly useful from policy point of view. This is because the country was divided into seven federal provinces in 2015 as per schedule 4 of the new Constitution of Nepal and there are no longer development regions in Nepal. The current system of seven provinces replaced an earlier system where Nepal was divided into five development regions. The new policies and programs in every sector including health are formulated considering the new provincial level structure. Thus, the provincial level information on stunting would highlight the current need of each province and this would help program planners and policy makers to design their interventions accordingly. However, province level data was only available for the year 2016. Hence, this study could not incorporate province level information. The causal inference between stunting and study variables is limited due to the cross sectional nature of the studies. This study doesn’t explain about caste or ethnicity, which might have influenced the inequalities in stunting. However, it has examined the relationship of stunting with mother’s education, wealth quintile etc. and have found significant association between them. The strength of this study would be that this study is based on the four large nationally representative population and large sample size warrant a high precision of the findings. Alongside, NDHS used the standardized tools, which are reliable and comparable to other developing countries.