title: Maternal overweight and obesity in early pregnancy and risk of infant mortality: a population based cohort study in Sweden.
abstract: OBJECTIVE
  To investigate associations between maternal overweight and obesity and infant mortality outcomes, including cause-specific mortality.
  
  
  METHODS
  Population based cohort study.
  
  
  METHODS
  1,857,822 live single births in Sweden 1992-2010.
  
  
  METHODS
  Associations between maternal body mass index (BMI) in early pregnancy and risks of infant, neonatal, and postneonatal mortality, overall and stratified by gestational length and by causes of infant death. Odds ratios were adjusted for maternal age, parity, smoking, education, height, country of birth, and year of delivery.
  
  
  RESULTS
  Infant mortality rates increased from 2.4/1000 among normal weight women (BMI 18.5-24.9) to 5.8/1000 among women with obesity grade 3 (BMI ≥ 40.0). Compared with normal weight, overweight (BMI 25.0-29.9) and obesity grade 1 (BMI 30.0-34.9) were associated with modestly increased risks of infant mortality (adjusted odds ratios 1.25 (95% confidence interval 1.16 to 1.35) and 1.37 (1.22 to 1.53), respectively), and obesity grade 2 (BMI 35.0-39.9) and grade 3 were associated with more than doubled risks (adjusted odds ratios 2.11 (1.79 to 2.49) and 2.44 (1.88 to 3.17)). In analyses stratified by preterm and term births, maternal BMI was related to risks of infant mortality primarily in term births (≥ 37 weeks), where risks of deaths due to birth asphyxia and other neonatal morbidities increased with maternal overweight and obesity. Obesity grade 2-3 was also associated with increased infant mortality due to congenital anomalies and sudden infant death syndrome.
  
  
  CONCLUSIONS
  Maternal overweight and obesity are associated with increased risks of infant mortality due to increased mortality risk in term births and an increased prevalence of preterm births. Maternal overweight and obesity may be an important preventable risk factor for infant mortality in many countries.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden stefan.johansson@ki.se.
authors.forename: Stefan
authors.initials: S
authors.lastname: Johansson
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, Michigan, United States.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Villamor
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Altman
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
authors.forename: Anna-Karin Edstedt
authors.initials: AK
authors.lastname: Bonamy
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Granath
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Solna, Karolinska University Hospital, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
authors.forename: Sven
authors.initials: S
authors.lastname: Cnattingius
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002423:Cause of Death; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D009765:Obesity / Q000453:epidemiology*; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult