Association Between Cesarean Birth and Risk of Obesity in Offspring in Childhood, Adolescence, and Early Adulthood.
Cesarean birth has been associated with higher risk of obesity in offspring, but previous studies have focused primarily on childhood obesity and have been hampered by limited control for confounders.



To investigate the association between cesarean birth and risk of obesity in offspring.



A prospective cohort study was conducted from September 1, 1996, to December 31, 2012, among participants of the Growing Up Today Study, including 22 068 offspring born to 15 271 women, followed up via questionnaire from ages 9 to 14 through ages 20 to 28 years. Data analysis was conducted from October 10, 2015, to June 14, 2016.



Birth by cesarean delivery.



Risk of obesity based on International Obesity Task Force or World Health Organization body mass index cutoffs, depending on age. Secondary outcomes included risks of obesity associated with changes in mode of delivery and differences in risk between siblings whose modes of birth were discordant.



Of the 22 068 offspring (20 950 white; 9359 male and 12 709 female), 4921 individuals (22.3%) were born by cesarean delivery. The cumulative risk of obesity through the end of follow-up was 13% among all participants. The adjusted risk ratio for obesity among offspring delivered via cesarean birth vs those delivered via vaginal birth was 1.15 (95% CI, 1.06-1.26; P = .002). This association was stronger among women without known indications for cesarean delivery (adjusted risk ratio, 1.30; 95% CI, 1.09-1.54; P = .004). Offspring delivered via vaginal birth among women who had undergone a previous cesarean delivery had a 31% (95% CI, 17%-47%) lower risk of obesity compared with those born to women with repeated cesarean deliveries. In within-family analysis, individuals born by cesarean delivery had 64% (8%-148%) higher odds of obesity than did their siblings born via vaginal delivery.



Cesarean birth was associated with offspring obesity after accounting for major confounding factors. Although additional research is needed to clarify the mechanisms underlying this association, clinicians and patients should weigh this risk when considering cesarean delivery in the absence of a clear indication.
Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts2Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts.
Changzheng
C
Yuan
Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts2Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts.
Audrey J
AJ
Gaskins
The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth College, Lebanon, New Hampshire.
Arianna I
AI
Blaine
Epidemiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.
Cuilin
C
Zhang
Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts5Department of Population Medicine, Harvard Medical School/Harvard Pilgrim Health Care Institute, Boston, Massachusetts.
Matthew W
MW
Gillman
Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts6Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts7Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts8Division of Adolescent/Young Adult Medicine, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts.
Stacey A
SA
Missmer
Department of Epidemiology, Brown University School of Public Health, Providence, Rhode Island.
Alison E
AE
Field
Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts2Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts6Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
Jorge E
JE
Chavarro
D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002585:Cesarean Section / Q000009:adverse effects* / Q000706:statistics & numerical data*; D002648:Child; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D063766:Pediatric Obesity / Q000453:epidemiology* / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult