title: [Secular variation of births, weight and length at birth: Local perspective].
abstract: OBJECTIVE
  To analyse the outcomes of births and anthropometric measurements at birth of children born between 1974 and 2011 at Limache Hospital (Valparaíso, Chile).
  
  
  METHODS
  Times series were constructed of births, weight and length at birth, and low weight and length at birth. The trend was modelled with linear and logistical regressions using splines to represent breaks in the trend by decade.
  
  
  RESULTS
  The series includes 17,574 births. There was an increase in births per year in the 1970s (30/year) and declines in them to 17 and 22 births/year in the 1980s and 1990s, respectively (P<.001), with no significant trend thereafter. Newborns from 2000 to 2011 weighed 266 grams more than those in the 1970s (P<.001), and have now reached a mean weight of 3,530 g. Low birthweight fell from 8% in the 1970s to 1.1% after 2000. Birth length increased by 1cm in the 37 years studied, with a reduction of low birth length from 7.6% to 2.1% during the period.
  
  
  CONCLUSIONS
  Live births in the Limache Hospital declined, and anthropometric measurements at birth improved in the years analysed. This information is useful in developing interventions, taking into account the possible selection biases that could distort these estimates and their interpretation.
authors: Doctor en Salud Pública, Departamento de Nutrición, Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address: hamigo@med.uchile.cl.
authors: Hugo
authors: H
authors: Amigo
authors: Médico, Departamento de Nutrición, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
authors: Patricia
authors: P
authors: Bustos
authors: Médico, Departamento de Nutrición, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
authors: Claudio
authors: C
authors: Vargas
authors: Alumno, Escuela de Medicina, Universidad de Chile, Santiago, Chile.
authors: Pablo
authors: P
authors: Iglesias
mesh_terms: D000886:Anthropometry; D001724:Birth Weight / Q000502:physiology*; D001827:Body Height / Q000502:physiology*; D002677:Chile; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D016014:Linear Models; D016015:Logistic Models; D008297:Male
keywords: Births; Nacimientos; Peso y longitud al nacer; Tendencias; Trends; Weight and length at birth