title: Reducing low birth weight: prioritizing action to address modifiable risk factors.
abstract: Low birth weight (LBW) affects 6.9% of all UK births and has remained largely unchanged for many years. The United Nations and the World Health Assembly have set targets to substantially reduce global incidence. Understanding the contribution of modifiable risk factors to the burden of LBW is required to ensure appropriate interventions are in place to achieve this reduction.
  
  
  
  Data from published studies on the risks from key modifiable factors were used alongside prevalence data from the Welsh population to calculate the population attributable risk for each factor individually and in combination.
  
  
  
  Fourteen risk factors accounted for nearly half of LBW births, and 60% of those to younger mothers (<25 years). Tobacco smoke exposure was the largest contributor. We estimated that smoking in pregnancy was a factor in one in eight LBW births, increasing to one in five for women aged under 25.
  
  
  
  Risk factors are interrelated and inequitably distributed within the population. Exposure to one factor increases the likelihood of exposure to a constellation of factors further increasing risk. Action to address LBW must consider groups where the risk factors are most prevalent and address these risk factors together using multi-component interventions.
authors.affiliation: Public Health Wales, Mold, Flintshire CH7 1PZ, UK.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Johnson
authors.affiliation: Public Health Wales, Mold, Flintshire CH7 1PZ, UK.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Jones
authors.affiliation: Cardiff University School of Medicine, Heath Park, Cardiff CF14 4YS, UK.
authors.forename: Shantini
authors.initials: S
authors.lastname: Paranjothy
mesh_terms: D000465:Algorithms; D016208:Databases, Factual; D005260:Female; D006293:Health Promotion; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D012307:Risk Factors; D040242:Risk Reduction Behavior; D006113:United Kingdom; D055815:Young Adult
keywords: low birth weight; modifiable risk factors; population attributable risk; pregnancy; tobacco