title: High gestational weight gain and the risk of preterm birth and low birth weight: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Many women have high gestational weight gain (GWG), but potential neonatal consequences are not yet well quantified. We sought to determine the relationship between high GWG and preterm birth (PTB) and low birth weight (LBW) in singleton births.
  
  
  METHODS
  We searched Medline and Embase and reference lists.
  
  
  METHODS
  Two assessors independently performed all steps. We selected studies assessing high total or weekly GWG on PTB (< 37 weeks) and LBW (< 2500 grams).
  
  
  METHODS
  Thirty-eight studies, 24 cohort and 14 case-control, were included involving 2 124 907 women. Most contained unadjusted data. Women with high total GWG had a decreased risk overall of PTB < 37 weeks (relative risk [RR] 0.75; 95% CI 0.60 to 0.96), PTB 32 to 36 weeks (RR 0.70; 95% CI 0.70 to 0.71), and < 32 weeks (RR 0.87; 95% CI 0.85 to 0.90). High GWG was associated with lower risk of LBW (RR 0.64; 95% CI 0.53 to 0.78). Women with the highest GWG had lower risks of LBW (RR 0.55; 95% CI 0.32 to 0.94) than women with moderately high GWG (RR 0.73; 95% CI 0.60 to 0.89). Women with the highest weekly GWG had greater risks of PTB (RR 1.51; 95% CI 1.47 to 1.55) than women with moderately high weekly GWG (RR 1.09; 95% CI 1.05 to 1.13). Women with high weekly GWG were at increased risk of PTB 32 to 36 weeks (RR 1.14; 95% CI 1.10 to 1.17 and < 32 weeks (RR 1.81; 95% CI 1.73 to 1.90).
  
  
  CONCLUSIONS
  Although women with high total GWG have lower unadjusted risks of PTB and LBW, high weekly GWG is associated with increased PTB, and more adjusted studies are needed, as are more studies in obese women. Potential benefits of high GWG for the infant must be balanced against maternal risks and other known infant risks such as high birth weight.
authors.affiliation: Division of Maternal-Fetal Medicine, McMaster University, Hamilton, ON; Department of Obstetrics and Gynecology, McMaster University, Hamilton, ON; Department of Radiology, McMaster University, Hamilton, ON; Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: McDonald
authors.affiliation: Department of Obstetrics and Gynecology, First Affiliated Hospital of Xi'an Jiao Tong University, Shaanxi Province, People's Republic of China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Han
authors.affiliation: Faculty of Health Sciences, McMaster University, Hamilton, ON.
authors.forename: Sohail
authors.initials: S
authors.lastname: Mulla
authors.affiliation: Faculty of Health Sciences, McMaster University, Hamilton, ON.
authors.forename: Olha
authors.initials: O
authors.lastname: Lutsiv
authors.affiliation: Faculty of Health Sciences, McMaster University, Hamilton, ON.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON.
authors.forename: Joseph
authors.initials: J
authors.lastname: Beyene
authors.affiliation: See Appendix.
authors.lastname: Knowledge Synthesis Group
authors.affiliation: Department of Paediatrics, Mount Sinai Hospital and Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON.
authors.forename: Prakesh
authors.initials: P
authors.lastname: Shah
authors.affiliation: Department of Paediatrics, Mount Sinai Hospital and Departments of Paediatrics, Obstetrics and Gynaecology, and Health Policy, Management and Evaluation, University of Toronto, ON.
authors.forename: Arne
authors.initials: A
authors.lastname: Ohlsson
authors.affiliation: Department of Paediatrics, Mount Sinai Hospital and Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON.
authors.forename: Vibhuti
authors.initials: V
authors.lastname: Shah
authors.affiliation: Department of Obstetrics and Gynecology, Mount Sinai Hospital and University of Toronto, Toronto, ON.
authors.forename: Kellie E
authors.initials: KE
authors.lastname: Murphy
authors.affiliation: Division of Maternal-Fetal Medicine, Departments of Obstetrics & Gynecology, Clinical Epidemiology & Biostatistics, and Diagnostic Imaging, McMaster University, Hamilton, ON.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: McDonald
authors.affiliation: Department of Obstetrics and Gynecology, McMaster University, Hamilton, ON.
authors.forename: Eileen
authors.initials: E
authors.lastname: Hutton
authors.affiliation: Faculty of Nursing, University of Alberta, Edmonton, AB.
authors.forename: Christine
authors.initials: C
authors.lastname: Newburn-Cook
authors.affiliation: Faculty of Nursing, University of Calgary, Calgary, AB.
authors.forename: Corine
authors.initials: C
authors.lastname: Frick
authors.affiliation: Dalla Lana School of Public Health, University of Toronto and Toronto Public Health, Toronto, ON.
authors.forename: Fran
authors.initials: F
authors.lastname: Scott
authors.affiliation: Department of Obstetrics and Gynaecology, Dalhousie University, Halifax, NS.
authors.forename: Victoria
authors.initials: V
authors.lastname: Allen
authors.affiliation: McMaster University, Hamilton, ON.
authors.forename: Joseph
authors.initials: J
authors.lastname: Beyene
authors.affiliation: McMaster University, Hamilton, ON.
authors.forename: John D
authors.initials: JD
authors.lastname: Cameron
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D016239:MEDLINE; D008429:Maternal Welfare; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012307:Risk Factors; D015430:Weight Gain