title: Low gestational weight gain and the risk of preterm birth and low birthweight: a systematic review and meta-analyses.
abstract: BACKGROUND
  Low gestational weight gain is common, with potential adverse perinatal outcomes.
  
  
  OBJECTIVE
  To determine the relation between low gestational weight gain and preterm birth and low birthweight in singletons in developing and developed countries.
  
  
  METHODS
  Medline, EMBASE and reference lists were searched, identifying 6,283 titles and abstracts.
  
  
  METHODS
  Following the MOOSE consensus statement, two assessors independently reviewed titles, abstracts, full articles, extracted data and assessed quality.
  
  
  RESULTS
  Fifty-five studies, 37 cohort and 18 case-control, were included, involving 3,467,638 women. In the cohort studies (crude data, generally supported where available by adjusted data and case-control studies), women with low total gestational weight gain had increases in preterm birth <37 weeks [RR 1.64 (95%CI 1.62-1.65)], 32-36 weeks [RR 1.39 (95%CI 1.38-1.40)] and ≤ 32 weeks [RR 3.80 (95%CI 3.72-3.88)]. Low total gestational weight gain was associated with increased risks of low birthweight <2,500 g [RR 1.85 (95%CI 1.72-2.00)], in developing and developed countries [RR 1.84 (95%CI 1.71-1.99) and RR 3.02 (95%CI 1.37-6.63), respectively], 1,500-2,500 g [RR 2.02 (95%CI 1.88-2.17)] and <1,500 g (RR 2.00 (95%CI 1.67-2.40)]. Women with low weekly gestational weight gain were at increased risk of preterm birth [RR 1.56 (95%CI 1.26-1.94)], 32-36 weeks [RR 2.43 (95%CI 2.37-2.50)] and ≤ 32 weeks [RR 2.31 (95%CI 2.20-2.42)] but not low birthweight [RR 1.64 (95%CI 0.89-3.02)].
  
  
  CONCLUSIONS
  In this systematic review, we determined that singletons born to women with low total gestational weight gain have higher risks of preterm birth and low birthweight, with the lower the gain, the higher the risks.
authors.affiliation: Department of Obstetrics and Gynecology, First Affiliated Hospital of Xi'an Jiao Tong University, Shaanxi Province, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Han
authors.forename: Olha
authors.initials: O
authors.lastname: Lutsiv
authors.forename: Sohail
authors.initials: S
authors.lastname: Mulla
authors.forename: Allison
authors.initials: A
authors.lastname: Rosen
authors.forename: Joseph
authors.initials: J
authors.lastname: Beyene
authors.forename: Sarah D
authors.initials: SD
authors.lastname: McDonald
mesh_terms: D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight / Q000502:physiology*; D007231:Infant, Newborn; D011247:Pregnancy / Q000502:physiology*; D047928:Premature Birth / Q000503:physiopathology*; D012306:Risk; D015430:Weight Gain / Q000502:physiology*