title: Revisiting the 'Low BirthWeight paradox' using a model-based definition.
abstract: BACKGROUND
  Immigrant mothers in Spain have a lower risk of delivering Low BirthWeight (LBW) babies in comparison to Spaniards (LBW paradox). This study aimed at revisiting this finding by applying a model-based threshold as an alternative to the conventional definition of LBW.
  
  
  METHODS
  Vital information data from Madrid was used (2005-2006). LBW was defined in two ways (less than 2500g and Wilcox's proposal). Logistic and linear regression models were run.
  
  
  RESULTS
  According to common definition of LBW (less than 2500g) there is evidence to support the LBW paradox in Spain. Nevertheless, when an alternative model-based definition of LBW is used, the paradox is only clearly present in mothers from the rest of Southern America, suggesting a possible methodological bias effect.
  
  
  CONCLUSIONS
  In the future, any examination of the existence of the LBW paradox should incorporate model-based definitions of LBW in order to avoid methodological bias.
authors.affiliation: Centre for Economic Demography, Lund University, Lund, Sweden. Electronic address: sol.juarez@ekh.lu.se.
authors.forename: Sol
authors.initials: S
authors.lastname: Juárez
authors.affiliation: Department of Population Studies, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: George B
authors.initials: GB
authors.lastname: Ploubidis
authors.affiliation: Department of Population Studies, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Lynda
authors.initials: L
authors.lastname: Clarke
mesh_terms: D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D015233:Models, Statistical; D012016:Reference Values; D013030:Spain
keywords: Bajo peso; Birthweight; España; Immigrant; Inmigrantes; Inmigrantes laborales; Low birthweight; Migrant workers; Peso al nacer; Spain