linear growth retardation , or stunting , which is a manifestation of chronic malnutrition , is highly prevalent in under - developed and developing countries.[14 ] according to the world health organization , 215 million children were stunted in 2000 throughout the world . the national data from 
iranian national study of malnutrition prevalence  in 2005 has indicated that 4.7% of iranian children are affected by stunting .
earlier studies have shown that child 's stunting is associated with concurrent , and possibly later , delayed mental and motor development .
the adverse effects of stunting could affect the adulthood by limiting work capacity owing to reduced muscle mass and increasing obstetric risks in women .
although , several studies have identified determinants of stunting in different populations,[51015 ] limited data are available indicating its associates among iranian children .
earlier studies have identified low birth weight , inadequate child care , feeding practice and birth order as a probable correlates of stunting # 94 ; wamani , 2007 # 82 ) .
it also has been shown that birth weight , breast feeding status , mothers age , family size , socio - economic status and birth order are associated with a higher prevalence of stunting among iranian children.[51822 ] previous studies have been limited in sample size and their sampling procedure ; such that their findings can not be easily extrapolated to other parts of the country .
it remains unknown if the determinants of stunting in a metropolitan area like tehran are different from those in deprived regions of the country .
this study was , therefore , conducted to investigate determinants of stunting in first grade primary school children of tehran .
in this case - control study , participants were selected by multistage cluster random sampling method from 5 districts of tehran in 2007 .
first , 42 public schools ( 19 schools for girls and 23 for boys ) were randomly selected based on proportional to size method in each district . in each selected school , all first grade pupils aged 7 years old were invited to participate in the study ( n = 3147 , 1343 boys and 1804 girls ) .
stunting was defined as height for age less than the 5 percentile of cdc2000 cut - off points .
based on this definition , 86 stunted children were identified and considered as case group in the current study . after matching for age , sex and residence area , 308 non - stunted children ( height for age more than the 5 percentile of cdc2000 cut - off points ) were randomly selected as control group .
the study was approved ethically by research ethics committee of national nutrition and food technology research institute , tehran , iran and all participants provided informed written consent forms .
required data about children 's birth weight and height , duration of breastfeeding and family demographic characteristics ( including family size , parity , parents job , parents; education , marital status , mothers age , and home ownership ) were collected by trained nutritionists using questionnaires .
anthropometric measurements were done in all participants by two trained nutritionists and were randomly re - checked by a senior investigator ( fe ) .
weight was measured by means of a portable calibrated digital scale ( breuer , germany ) to the nearest 0.1 kg in light clothing without shoes .
height was measured according to a standard protocol to the nearest 0.1 cm using height measure ( seca 214 , germany ) .
mothers weight and height were measured by standard methods and fathers weight and height were collected through self - reporting .
data were analyzed using statistical package for social science ( spss inc , version 14 ) . to ensure normal distribution of variables , kolmogrov - smirnov test was applied .
continuous variables were compared using independent samples t - test between stunted and non - stunted children .
distribution of participants in terms of categorical variables was examined through the use of chi - square test .
multivariate logistic regression analysis was applied to identify the determinants of stunting . in these analyses ,
first the continuous variables were entered into the models and then these variables were treated as categorical variables .
in this case - control study , participants were selected by multistage cluster random sampling method from 5 districts of tehran in 2007 .
first , 42 public schools ( 19 schools for girls and 23 for boys ) were randomly selected based on proportional to size method in each district . in each selected school , all first grade pupils aged 7 years old were invited to participate in the study ( n = 3147 , 1343 boys and 1804 girls ) .
stunting was defined as height for age less than the 5 percentile of cdc2000 cut - off points .
based on this definition , 86 stunted children were identified and considered as case group in the current study . after matching for age , sex and residence area , 308 non - stunted children ( height for age more than the 5 percentile of cdc2000 cut - off points ) were randomly selected as control group .
the study was approved ethically by research ethics committee of national nutrition and food technology research institute , tehran , iran and all participants provided informed written consent forms .
required data about children 's birth weight and height , duration of breastfeeding and family demographic characteristics ( including family size , parity , parents job , parents; education , marital status , mothers age , and home ownership ) were collected by trained nutritionists using questionnaires .
anthropometric measurements were done in all participants by two trained nutritionists and were randomly re - checked by a senior investigator ( fe ) .
weight was measured by means of a portable calibrated digital scale ( breuer , germany ) to the nearest 0.1 kg in light clothing without shoes .
height was measured according to a standard protocol to the nearest 0.1 cm using height measure ( seca 214 , germany ) .
mothers weight and height were measured by standard methods and fathers weight and height were collected through self - reporting .
data were analyzed using statistical package for social science ( spss inc , version 14 ) . to ensure normal distribution of variables , kolmogrov - smirnov test was applied .
continuous variables were compared using independent samples t - test between stunted and non - stunted children .
distribution of participants in terms of categorical variables was examined through the use of chi - square test .
multivariate logistic regression analysis was applied to identify the determinants of stunting . in these analyses ,
first the continuous variables were entered into the models and then these variables were treated as categorical variables .
it was more prevalent in girls ( 4.4% ) than boys ( 2.8% , p < 0.05 ) .
mean age of the studied children was 82.3 month with no significant difference between cases and controls .
stunted children were more likely to be thin compared with non - stunted children ( weight : 17.9  1.8 vs. 24.8  6.3 , p < 0.001 ) .
mean birth weight ( 2860  570 vs. 3230  530 g , p < 0.001 ) was also lower in stunted children than non - stunted counterparts ; however , their mean birth length was not significantly different ( 48.9  4.0 vs. 49.8  4.6 cm , p = 0.19 ) .
stunted children were less likely to be exclusively breastfed for the first 6 months of their life ( 83% vs. 91% , p = 0.045 ) and less likely to be first born in terms of birth order ( 36.7 vs. 56.8% , p = 0.002 ) compared with non - stunted children .
they were born to older mothers and to parents with lower weight and height than non - stunted children .
characteristics of the study participants multivariate adjusted odds ratios of stunting for different contributing factors are presented in table 2 .
it has been found that birth weight ( odds ratio : 0.31 ; 95% ci : 0.14 - 0.66 ) and fathers height ( odds ratio : 0.89 ; 95% ci : 0.84 - 0.95 ) were protectively associated with stunting .
no significant associations were seen between other factors and stunting when these factors were treated as continuous variables .
determinants ( continuous variables ) of stunting among school - aged children when the variables were treated as categorical [ table 3 ] , we found that children with a birth weight of > 3000 g were less likely to be stunted ( or : 0.25 : 95% ci : 0.11 - 0.54 ) compared with those with a birth weight of < 3000 g. being born to older mothers ( > 35 years ) was associated with greater odds of being stunted ( 3.01 ; 1.19 - 7.60 ) compared with being born to younger mothers ( < 35 years ) .
those with a fathers height of > 160 cm were less likely to be stunted ( 0.04 ; 0.005 - 0.37 ) than those whose fathers height was less than 160 cm .
birth weight , fathers height and maternal age were the main contributing factors to stunting in the studied population .
the prevalence of stunting in this study was in agreement with the one reported by national study of malnutrition prevalence in iranian children .
it seems that the prevalence of stunting has been decreased in the past decade in the country .
the decreasing trend of stunting has been reported in south east asia , where the stunting has reduced in elementary school children from 52.4%in 1998 to 32.8% in 2000 . worldwide stunting prevalence
this can be explained by improved primary health care during pregnancy and early childhood , breastfeeding and growth monitoring . in this study ,
the prevalence of low birth weight and short duration of breastfeeding ( < 6 mo ) was higher in cases than that in controls .
increased requirements in these infants , additional amounts of nutrients are needed for these babies to reach normal height growth .
findings of the current study about breastfeeding are in agreement with those of marquis et al . , in peru and
semba et al . , in indonesia and bangladesh which indicated that short duration of breastfeeding was positively related to prevalence of stunting
. short duration of breastfeeding would prohibit adequate dietary intakes of energy , protein and micronutrients required for normal height growth .
this finding is in line with earlier studies among brazilian , mexican and pakistani children .
birth weight has also been reported as a strong predictor of child size in later life among children with intra - uterine growth retardation ( iugr ) .
low birth weight and subsequent stunting could be induced by maternal under - nutrition during pregnancy . in the current study
adequate nutrition during pregnancy would result in increased birth weight and in turn would improve child growth in later life .
this finding is in agreement with previously reported ones . in egypt , children born to mothers aged 35 years showed a higher prevalence of stunting than children born to mothers in other age groups .
maternal age has also been reported as a determinant factor of stunting in south african children .
the effect of the age of the mother on child health outcomes has also been explored in several studies . in the case of india , raj et al .
, showed that children born to mothers who were married below the age of 18 were at a higher risk of stunting and underweight compared to children of women who had married at age 18 or older .
although , several studies have reported the importance of mothers young age at pregnancy on health outcomes of children , limited data have focused on older age .
the current findings highlight the importance of old age of mothers as a contributing factor to stunting . as we all know socioeconomic status and dietary intakes
we tried to collect data on economical status of the households ; however , after completion of the study , we found that these data are not reliable .
one might suggest the use of living district as a proxy of socioeconomic status . in the current study , when we explored the frequency of stunting in different districts of tehran (
5 districts were selected in this study ) , we failed to find a significant difference .
due to the inclusion of children from different socioeconomic status in the current study , the findings can easily be extrapolated to the tehrani children , however , more caution are required about the generalizability of the findings to the whole country .
we found that birth weight , maternal age and fathers height are the major contributing factors to stunting in this group of iranian children .
furthermore , taking into account the determinants of stunting might help policy makers designing appropriate interventions .
 background : limited data are available indicating associates of stunting among iranian children . 
 this study was conducted to investigate determinants of stunting in first grade primary school children of tehran in 2007.method:in this case - control study , 3147 school children were selected by multistage cluster random sampling method from 5 districts of tehran . 
 anthropometric measurements were done and stunting was defined as height for age less than the 5th percentile of cdc2000 cut - off points . 
 eighty six stunted children were identified and considered as case group . after matching for age , sex and residence area , 
 308 non - stunted children were randomly selected as control group . 
 required data were collected by trained nutritionists using questionnaires.results:stunting was prevalent among 3.7% of the study population ( girls 4.4% vs. boys 2.8% , p < 0.05 ) . 
 mean age of the studied children was 82.3 month . 
 children with a birth weight of > 3000 g were less likely to be stunted ( or : 0.25 : 95% ci : 0.11 - 0.54 ) compared with those with a birth weight of < 3000 g. being born to older mothers ( > 35 years ) was associated with greater odds of being stunted ( 3.01 ; 1.19 - 7.60 ) compared with being born to younger mothers ( < 35 years ) . 
 those with fathers height of > 160 cm were less likely to be stunted ( 0.04 ; 0.005 - 0.37 ) than those whose fathers height was less than 160 cm.conclusions:we found that birth weight , maternal age and fathers height are the major contributing factors to stunting in this group of iranian children . taking into account the determinants of stunting 
 might help policy makers designing appropriate interventions . 
INTRODUCTION
METHODS
Participants
Data collection
Statistical analysis
RESULTS
DISCUSSSION
CONCLUSIONS