title: Length and weight growth trends for children less than two years old in Zanjan, Iran: Longitudinal modeling.
abstract: BACKGROUND
  Growth failure in children less than five years old can lead to the serious complications such as increased mortality, learning difficulties or physical disability. The aim of this study was to investigate the nonorganic factors affecting the growth trend in less than two years children living in Zanjan, Iran.
  
  
  METHODS
  This longitudinal study was conducted on a sample of 3566 children less than two years old in Zanjan. Weight and length growth trends were recorded as ordinal variables and analyzed by longitudinal marginal model.
  
  
  RESULTS
  About 12% (n=289) and 8% (n=212) of children had at least one decline/stagnation in the weight and length growth curve, respectively. Based on the marginal model, the effect of the child's age and residence area on the weight and length growth trends were statistically significant (p<0.05).
  
  
  CONCLUSIONS
  Given the relatively high prevalence of growth failure among studied children less than two years old in rural areas of Zanjan, raising the awareness of parents in rural areas about feeding and nutritional behaviors of children seems an important issue. Additionally, healthcare providers should mostly focus on monitoring the growth of children older than 12 months.
authors: PhD Student of Biostatistics, Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. nasim.vahabi@modares.ac.ir.
authors: Nasim
authors: N
authors: Vahabi
authors: Professor of Biostatistics, Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. kazem_an@modares.ac.ir.
authors: Anoshirvan
authors: A
authors: Kazemnejad
authors: PhD Student of Biostatistics, Department of Biostatistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. r.fallahvalamdehi@modares.ac.ir.
authors: Ramazan
authors: R
authors: Fallah
keywords: Weight growth trend; length growth trend; longitudinal data; marginal model