title: Does vaginal delivery mitigate or strengthen the intergenerational association of overweight and obesity? Findings from the Boston Birth Cohort.
abstract: The intergenerational association of obesity may be driven by mother-to-newborn transmission of microbiota at birth. Yet cesarean delivery circumvents newborn acquisition of vaginal microbiota, and has been associated with greater childhood adiposity. Here we examined the independent and joint associations of maternal pre-pregnancy body mass index (BMI; kg m-2) and delivery mode with childhood overweight or obesity.
  
  
  
  We prospectively followed 1441 racially and ethnically diverse mother-child dyads in the Boston Birth Cohort until age 5 years (range: 2.0-8.0 years). We used logistic regression to examine the independent and joint associations of delivery mode (cesarean and vaginal delivery) and pre-pregnancy BMI with childhood overweight or obesity (age-sex-specific BMI ⩾85th percentile).
  
  
  
  Of 1441 mothers, 961 delivered vaginally and 480 by cesarean. Compared with vaginally delivered children, cesarean delivered children had 1.4 (95% confidence interval (CI) 1.1-1.8) times greater odds of becoming overweight or obese in childhood, after adjustment for maternal age at delivery, race/ethnicity, education, air pollution exposure, pre-pregnancy BMI, pregnancy weight gain and birth weight. Compared with children born vaginally to normal weight mothers, after multivariable adjustment, odds of childhood overweight or obesity were highest in children born by cesarean delivery to obese mothers (odds ratio (OR): 2.8; 95% CI: 1.9-4.1), followed by children born by cesarean delivery to overweight mothers (OR: 2.2; 95% CI: 1.5-3.2), then children born vaginally to obese mothers (OR: 1.8; 95% CI: 1.3-2.6) and finally children born vaginally to overweight mothers (OR: 1.7; 95% CI: 1.2-2.3).
  
  
  
  In our racially and ethnically diverse cohort, cesarean delivery and pre-pregnancy overweight and obesity were associated with childhood overweight or obesity. Needed now are prospective studies that integrate measures of the maternal and infant microbiome, and other potentially explanatory covariates, to elucidate the mechanisms driving this association and to explore whether exposure to vaginal microbiota in cesarean delivered newborns may be an innovative strategy to combat the intergenerational cycle of obesity.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.|Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: N T
authors.initials: NT
authors.lastname: Mueller
authors.affiliation: Center for Clinical and Epidemiological Research, The Eye Hospital of Wenzhou Medical University, Wenzhou, China.|Department of Preventive Medicine, School of Environmental Science and Public Health, Wenzhou Medical University, Wenzhou, China.|Department of Population, Family and Reproductive Health, Center on the Early Life Origins of Disease, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: G
authors.initials: G
authors.lastname: Mao
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.|Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD, USA.|Division of General Internal Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: W L
authors.initials: WL
authors.lastname: Bennet
authors.affiliation: Inova Translational Medicine Institute, Fairfax, VA, USA.|Inova Children's Hospital, Fairfax, VA, USA.|Pediatric Specialists of Virginia, Fairfax, VA, USA.|Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Hourigan
authors.affiliation: Human Microbiome Program, New York University School of Medicine, New York, NY, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Dominguez-Bello
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.|Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD, USA.|Division of General Internal Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Appel
authors.affiliation: Department of Population, Family and Reproductive Health, Center on the Early Life Origins of Disease, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: X
authors.initials: X
authors.lastname: Wang
mesh_terms: D000328:Adult; D017668:Age of Onset; D001724:Birth Weight; D015992:Body Mass Index; D001900:Boston / Q000453:epidemiology; D002585:Cesarean Section / Q000009:adverse effects / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D064307:Microbiota / Q000276:immunology*; D009035:Mothers; D063766:Pediatric Obesity / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D014621:Vagina / Q000382:microbiology*