title: Contribution of prepregnancy body mass index and gestational weight gain to adverse neonatal outcomes: population attributable fractions for Canada.
abstract: BACKGROUND
  Low or high prepregnancy body mass index (BMI) and inadequate or excess gestational weight gain (GWG) are associated with adverse neonatal outcomes. This study estimates the contribution of these risk factors to preterm births (PTBs), small-for-gestational age (SGA) and large-for-gestational age (LGA) births in Canada compared to the contribution of prenatal smoking, a recognized perinatal risk factor.
  
  
  METHODS
  We analyzed data from the Canadian Maternity Experiences Survey. A sample of 5,930 women who had a singleton live birth in 2005-2006 was weighted to a nationally representative population of 71,200 women. From adjusted odds ratios, we calculated population attributable fractions to estimate the contribution of BMI, GWG and prenatal smoking to PTB, SGA and LGA infants overall and across four obstetric groups.
  
  
  RESULTS
  Overall, 6% of women were underweight (<18.5 kg/m(2)) and 34.4% were overweight or obese (≥25.0 kg/m(2)). More than half (59.4%) gained above the recommended weight for their BMI, 18.6% gained less than the recommended weight and 10.4% smoked prenatally. Excess GWG contributed more to adverse outcomes than BMI, contributing to 18.2% of PTB and 15.9% of LGA. Although the distribution of BMI and GWG was similar across obstetric groups, their impact was greater among primigravid women and multigravid women without a previous PTB or pregnancy loss. The contributions of BMI and GWG to PTB and SGA exceeded that of prenatal smoking.
  
  
  CONCLUSIONS
  Maternal weight, and GWG in particular, contributes significantly to the occurrence of adverse neonatal outcomes in Canada. Indeed, this contribution exceeds that of prenatal smoking for PTB and SGA, highlighting its public health importance.
authors: Maternal and Infant Health Section, Health Surveillance and Epidemiology Division, Public Health Agency of Canada, 785 Carling Avenue, 6804A 4th Floor, Ottawa, Ontario, K1A 0 K9, Canada. susie.dzakpasu@phac-aspc.gc.ca.
authors: Susie
authors: S
authors: Dzakpasu
authors: Reproductive Care Program of Nova Scotia, Halifax, Nova Scotia, Canada. John.Fahey@iwk.nshealth.ca.
authors: John
authors: J
authors: Fahey
authors: Department of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL, U.S.A. rkirby@health.usf.edu.
authors: Russell S
authors: RS
authors: Kirby
authors: Departments of Paediatrics and Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada. Suzanne.Tough@albertahealthservices.ca.
authors: Suzanne C
authors: SC
authors: Tough
authors: Department of Obstetrics and Gynaecology, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada. bevchalmers1@gmail.com.
authors: Beverley
authors: B
authors: Chalmers
authors: College of Nursing, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada. Maureen.Heaman@umanitoba.ca.
authors: Maureen I
authors: MI
authors: Heaman
authors: Maternal and Infant Health Section, Health Surveillance and Epidemiology Division, Public Health Agency of Canada, 785 Carling Avenue, 6804A 4th Floor, Ottawa, Ontario, K1A 0 K9, Canada. Sharon.Bartholomew@phac-aspc.gc.ca.
authors: Sharon
authors: S
authors: Bartholomew
authors: Department of Family and Community Medicine, University of Toronto, Mount Sinai Hospital, Toronto, Ontario, Canada. abiringer@mtsinai.on.ca.
authors: Anne
authors: A
authors: Biringer
authors: Midwifery Education Program, Laurentian University, Sudbury, Ontario, Canada. ldarling@idirect.com.
authors: Elizabeth K
authors: EK
authors: Darling
authors: Perinatal Services British Columbia, Provincial Health Services Authority, Vancouver, British Columbia, Canada. LLee-02@phsa.ca.
authors: Lily S
authors: LS
authors: Lee
authors: Departments of Obstetrics & Gynecology, Radiology, and Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Canada. mcdonals@mcmaster.ca.
authors: Sarah D
authors: SD
authors: McDonald
mesh_terms: D000328:Adult; D001724:Birth Weight; D015992:Body Mass Index; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D011256:Pregnancy Outcome / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D013851:Thinness / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D015430:Weight Gain
references: PLoS One. 2013;8(1):e53749
references: 23341993
references: Health Rep. 2008 Jun;19(2):77-84
references: 18642521
references: Lancet. 2011 Apr 16;377(9774):1331-40
references: 21496916
references: BMC Med Res Methodol. 2009 Jan 23;9:7
references: 19166593
references: Paediatr Perinat Epidemiol. 2013 Jan;27(1):54-61
references: 23215712
references: J Obstet Gynaecol Can. 2012 Feb;34(2):159-171
references: 22340065
references: BMC Pregnancy Childbirth. 2008 Jan 08;8:1
references: 18179721
references: Health Rep. 2006 Aug;17(3):9-25
references: 16981483
references: Matern Child Health J. 2007 Mar;11(2):137-44
references: 17066316
references: Paediatr Perinat Epidemiol. 2007 Jan;21(1):5-14
references: 17239174
references: Int J Epidemiol. 2011 Feb;40(1):65-101
references: 21097954
references: Matern Child Health J. 2011 Oct;15(7):1119-26
references: 20711804
references: J Obstet Gynaecol Can. 2008 Mar;30(3):207-216
references: 18364098
references: Lancet. 2008 Jan 5;371(9606):75-84
references: 18177778
references: Semin Perinatol. 2002 Aug;26(4):286-95
references: 12211619
references: South Med J. 2005 Apr;98(4):411-5
references: 15898514
references: PLoS One. 2014 Aug 13;9(8):e105155
references: 25119107
references: Obstet Gynecol. 2005 Mar;105(3):633-8
references: 15738036
references: Am J Obstet Gynecol. 2011 Oct;205(4):333.e1-6
references: 21784404
references: BMC Med Res Methodol. 2002 Jun 17;2:8
references: 12069695
references: Cochrane Database Syst Rev. 2013 Oct 23;(10):CD001055
references: 24154953
references: Obstet Gynecol. 2014 Apr;123(4):737-44
references: 24785599
references: Matern Child Health J. 2014 Oct;18(8):1905-11
references: 24474592
references: Am J Clin Nutr. 2008 Jun;87(6):1750-9
references: 18541565
references: Am J Clin Nutr. 2010 Jun;91(6):1642-8
references: 20357043
references: Matern Child Nutr. 2014 Jul;10(3):315-26
references: 22783998
references: J Nutr. 2003 May;133(5 Suppl 2):1592S-1596S
references: 12730473
references: Am J Obstet Gynecol. 2001 Oct;185(4):845-9
references: 11641663
references: Popul Health Metr. 2012 Nov 20;10(1):22
references: 23167948
references: BJOG. 2012 Feb;119(3):283-90
references: 22168897
references: BMJ. 2010 Jul 20;341:c3428
references: 20647282