Underweight in 6.3%, stunting in 15.7%, and wasting in 2.7% of subjects was seen in 2013 with a higher rate in boys. According to UNICEF report, the prevalence of underweight, stunting, and wasting among Iranian five-year olds was 11%, 15%, and 5%, respectively. In Iran, several studies have found the prevalence of underweight, stunting and wasting 4.3%, 8.7%, and 7.5% in west Azarbaijan province (
16) and 7.5%, 12.5%, and 4.4% in Khorasan province (
17). Worldwide about 50% of preschool children are malnourished ranging from 64.0% in Bangladesh to 16.0% in China (
18).
In sixty countries with data since 2006, the median prevalence of wasting is 7.1%, ranging from 0.6% in Peru to 21% in the last survey in Sudan; very high rates of wasting are also observed in Niger (15.5%), Chad (15.6%), Bangladesh (17.5%), and India (20.0%) (
19).
The prevalence of underweight, stunting and wasting among under-five-children in rural areas in China was 14.6%, 7.2% and 3.1%, respectively (
20). These were 4.5%, 8.5% and 3.9% in Portuguese (
21), and 27%, 37%, and 6% in Kenya (
22).
Compared with our findings, stunting is notable in north Iran and it is necessary to establish a control planning. Similar to other studies (
22,
23), we found sex differences of under nutrition indicating higher rates in boys.
In the present study, trends of under nutrition among the three ethnic groups are not similar. Although the index has decreased in Fars-natives and Sistanis, in Turkmans it has increased. The underweight has been unchanged in Fars-natives and in Sistani but it has doubled in Turkmans during 15 years. Stunting has decreased 28.7% in Fars-natives and 35.1% in Sistanis while it has increased up to 8.5% in Turkman children. Trend studies on community nutrition of ethnic groups are scarce while studies on overall trends have been established in some countries.
Globally, childhood stunting decreased from 34% to 27% and underweight decreased from 27% to 22% between 1990 and 2000 (
3). Stunting is predicted to reduce up to 22% by the next decade (
6). Underweight declined significantly from 25.1% in 1993 to 15.1% in 2008 in Ghana (
24). In China (
15) the prevalence of underweight and stunting among under-five children lowered by 24.4% in 2002 to 30.8%, in 2006. In Peru (
25) underweight dropped from 10.1% to 8.2% during 15 years and stunting decreased 19.6% in those children. In India (
26), a steady decrease in stunting was seen among rural children in 1992 - 2005, while the decline in underweight was greater between 1992 and 1998 than between 1998 and 2005. Based on UNICEF report, trends in stunting among under-five children in 1990s have been decreased in China (
27). In Kenya (
28), child under nutrition based on underweight has declined in most socio-demographic groups during 1993 to 2009. In that study, stunting was unchanged altogether, although this trend in boys aged 0 - 35 months significantly decreased and in girls aged 12 - 23 months significantly increased.
Factors associated with under nutrition reported in some studies (
20,
26,
29), are family income, provision of primary health care, low birth weight, gender, age, birth order, religion, maternal age, and maternal education. Association between socio-economic status and nutritional condition of ethnic groups has been reported differently in north Iran (
30,
31). In our study, the lowering trend of under nutrition in Fars-natives and Sistani children is in line with other studies but growing trend of it in Turkmans is unexpected. The social-behaviors in Turkman society differ from other ethnic groups in north Iran; possibly there are underlying factors for different food-behavior in this group. The role of food-behaviors of ethnicities residing in north Iranian should be evaluated in further studies.
Consistent with following studies, we have shown the poor economic status as a risk factor for malnutrition. Cultural status, income level, food behavior, and less health care were known as the risk factors for malnutrition (
32). Block (
33) believed that low income families are less aware of their food needs. In Iran (
34), socio-demographic factors influence nutritional education with improving health criteria. Thereby, more common under nutrition in Sistani children may be related to the poor economic status in this ethnic group. The socio-demography related factors as underlying causes of malnutrition in under-five-year children have been highlighted in our study.
We didn’t evaluate all of the factors that are associated with nutritional status, e.g. quality and quantity of food intake, or physical activities. Initially, ethnic groups have not been considered in sample size estimation, and age groups have not been compared among the three studies. These are our limiting study factors.
Under nutrition remains one of the health problems in under-five-year children in north Iran. Generally, under nutrition has declined from 1998 to 2004 while it has risen from 2004 to 2013. Physical growth in three studied ethnic groups is not similar. Stunting in Sistani children deeply decreased while in Turkman children slightly increased during this study. Poor economic status is a risk factor for under nutrition in this area. The changing of physical growth in Iranian northern children is remarkable. Further studies are necessary to evaluate the growth monitoring and socio-demography related factors on children of the three ethnic groups.