Stunting has steadily declined in Tanzania over the past 30 years, but challenges remain

Children are considered stunted when they are too short for their age – defined as height-for-age being more than minus two standard deviations below the World Health Organization (WHO) Child Growth Standards median. Stunting occurs when a child’s growth and development is impaired due to poor nutrition (during pre-conception, pregnancy and early childhood), repeated infection, and inadequate psychosocial stimulation. Stunting puts children at a significant disadvantage at the beginning of their lives and into adulthood. Children affected may never reach their full potential height or fully develop their cognitive abilities. They encounter challenges in learning at school, have lower earning potential as adults, face obstacles to engaging in their communities, and have increased likelihood of developing non-communicable diseases during adulthood.

Globally, 150.2 million children under the age of five were stunted in 2024. The 2030 global targets for stunting, in accordance with Sustainable Development Goal 2.2 (to end all forms of malnutrition) and the World Health Assembly global nutrition targets, are to reduce the number of stunted children to 90 million and to halve the number of children under five affected by stunting. While important progress has been made, the Joint Child Malnutrition Estimates (2025 edition) reveals that it is insufficient to meet these targets, and recent trends indicate a potential rise in stunting.

In 2024, nearly all stunted children were living in Asia (51%) and Africa (43%). The prevalence of stunting is notably higher among children living in low- and lower-middle-income countries. Central Africa is the most severely affected subregion, and Africa is the only region where the number of children with stunting has significantly increased. This might be related to women’s workload, as they shift from caring to being breadwinners, food systems failing to deliver nutritious diets for children, rises in disease outbreaks, climate change, conflict and displacement, slow progress in maternal and early-child nutrition, care, and health services due to financial crisis, and inequality and poverty. 

Progress in Tanzania

In Tanzania, however, considerable gains in children’s nutrition have been made, and Demographic and Health Surveys (DHS) data shows that stunting has decreased slowly over the last 30 years, from 50% in 1991/92 to 30% in 2022.

The DHS Program conducts nationally representative, repeated cross-sectional surveys in low- and middle-income countries to gather socioeconomic and demographic data, along with other health and development measures. Seven waves of the Tanzania DHS have been conducted between 1991/92 and 2022. As part of a Thrive project on stunting in Tanzania, we used this data to examine trends in stunting and the factors associated with the risk of being stunted among children under the age of five in Tanzania. The factors we identified relate to children, mothers and households.

Child-related factors

Birth weight is a strong predictor of stunting. Children with a low birth weight (below 2,500 grams) are more susceptible to health issues and disorders that can impair growth and development. In our study, close to half of children under five who were born with a low birth weight were stunted, compared to only around a quarter of children with a healthy birth weight of 3,500 grams or more. Stunting rates are at their highest in children of 18-24 months (40%) and 24-30 months (41%).

In terms of gender differences, over the last 30 years, boys under five have consistently had four to seven percentage points higher stunting rates than girls the same age. Girls have a 16% lower chance of being stunted. Previous research suggests that biological differences, higher caloric needs, greater susceptibility to pre-term birth among males, and gender roles, where girls spend more time with their mothers in the kitchen giving them chance to receive some foods when cooking is ongoing, may explain this trend.

Maternal characteristics

Mothers’ nutritional characteristics, defined by Body Mass Index (BMI), have consistently been closely correlated with the growth of newborn babies. In line with this, our study shows that mothers with a low BMI have a higher proportion of stunted children and that a higher maternal BMI correlates with lower risk of stunting.

Our findings also reinforce that increasing intervals between births (to 24 to 47 months) significantly reduces the risk of child stunting. Short intervals have been linked to adverse outcomes such as pre-term birth, low birth weight, and congenital abnormalities.

In addition, mothers attending more than four antenatal care visits is associated with a declining trend in stunting, decreasing from 42% in 1991/1992 to 26% in 2022. This is likely to be related to increased utilisation of antenatal services. A Northern Tanzania study revealed that women attending fewer than four visits had higher risks of delivering low birth weight infants, a key driver of stunting.

Our study also contributes to evidence on the complex relationship between breastfeeding duration and nutritional outcomes. Stunting rates for children breastfed for less than 12 months declined from 22% in 1991/92 to 17% in 2022, and stunting rates in children breastfed for over 12 months declined from 51% in 1991/92 to 38% in 1996. However, over time, children breastfed for more than 12 months consistently exhibit higher stunting prevalence compared to the overall rate, a pattern echoed in other studies.

One assumption could be that prolonged breastfeeding delays or substitutes complementary feeding, exposing children to inadequate nutrient intake. According to the 2022 Tanzania DHS, only 19% of children aged 6-23 months and 25% of women aged 15-49 years have a diversified diet. For most Tanzanians, diets are undiversified, with an average of 71% of all energy coming from staple foods that are often low in micronutrients, such as ugali (made from maize flour). Even in the wealthiest segment of the population, nearly 60% of energy is derived solely from staple foods. In addition, we found that 11% of children aged 6-59 months had received iron-containing supplements in the last 12 months at a health facility, and 53% had been given vitamin A supplements in the last six months.

Maternal education remains a consistent predictor of child nutritional status, both globally and within Tanzania (education is likely to enhance household income and mothers’ capacity to provide appropriate nutrition and hygiene, and to increase mothers’ awareness of healthcare and development). Indeed, our study suggests that mothers with no education have children with higher rates of stunting compared to those with a higher educational status.

Household-related factors

There is a clear disparity in stunting rates between households of different socioeconomic statuses; prevalence was greater in households with the lowest status (38.6%) compared to those with the highest (12.6%). Lower income households are likely to face multiple challenges where nutrition and sanitation are concerned, which can predispose children to stunting. Indeed, households with unimproved water access, unimproved sanitation and open defecation have higher stunting rates than at the national level. Repeated episodes of sickness affect children’s growth over time, and we see that when diarrhoea decreases (as it did among children under five between 1991 and 2022), so does stunting.

Regional differences were also noted; in 2022, the regions of the South West Highlands and Southern Highlands had a statistically significantly higher proportion of stunted children, at 37.8% and 46.2% respectively, compared to the Eastern region and Zanzibar, which had 22.8% and 17.1% respectively. It’s unfortunate that the regions with higher stunting are also known as regions with high food production. A study in one of these regions found that maternal workload, alcoholism, poor infant and young child feeding practices, poor access to health services, women and children violence, higher selling of food crops, and poor hygiene and sanitation were perceived to be associated with stunting.

Although child stunting has decreased in Tanzania over the past 30 years, it remains higher than the global average of 22%, raising serious concerns about the development and health of the country’s children. Combatting stunting – a multifaceted challenge – requires a multisectoral approach. It needs coordinated actions across health, agriculture, education and social protection to tackle the factors that contribute to stunting, including access to water and sanitation; socioeconomic inequalities; gender disparities; and region-specific challenges.

The study was recently published in PLOS One and was the focus of a recent Thrive webinar, which you can watch here.