title: Planned Repeat Cesarean Section at Term and Adverse Childhood Health Outcomes: A Record-Linkage Study.
abstract: BACKGROUND
  Global cesarean section (CS) rates range from 1% to 52%, with a previous CS being the commonest indication. Labour following a previous CS carries risk of scar rupture, with potential for offspring hypoxic brain injury, leading to high rates of repeat elective CS. However, the effect of delivery by CS on long-term outcomes in children is unclear. Increasing evidence suggests that in avoiding exposure to maternal bowel flora during labour or vaginal birth, offspring delivered by CS may be adversely affected in terms of energy uptake from the gut and immune development, increasing obesity and asthma risks, respectively. This study aimed to address the evidence gap on long-term childhood outcomes following repeat CS by comparing adverse childhood health outcomes after (1) planned repeat CS and (2) unscheduled repeat CS with those that follow vaginal birth after CS (VBAC).
  
  
  RESULTS
  A data-linkage cohort study was performed. All second-born, term, singleton offspring delivered between 1 January 1993 and 31 December 2007 in Scotland, UK, to women with a history of CS (n = 40,145) were followed up until 31 January 2015. Outcomes assessed included obesity at age 5 y, hospitalisation with asthma, learning disability, cerebral palsy, and death. Cox regression and binary logistic regression were used as appropriate to compare outcomes following planned repeat CS (n = 17,919) and unscheduled repeat CS (n = 8,847) with those following VBAC (n = 13,379). Risk of hospitalisation with asthma was greater following both unscheduled repeat CS (3.7% versus 3.3%, adjusted hazard ratio [HR] 1.18, 95% CI 1.05-1.33) and planned repeat CS (3.6% versus 3.3%, adjusted HR 1.24, 95% CI 1.09-1.42) compared with VBAC. Learning disability and death were more common following unscheduled repeat CS compared with VBAC (3.7% versus 2.3%, adjusted odds ratio 1.64, 95% CI 1.17-2.29, and 0.5% versus 0.4%, adjusted HR 1.50, 95% CI 1.00-2.25, respectively). Risk of obesity at age 5 y and risk of cerebral palsy were similar between planned repeat CS or unscheduled repeat CS and VBAC. Study limitations include the risk that women undergoing an unscheduled CS had intended to have a planned CS, and lack of data on indication for CS, which may confound the findings.
  
  
  CONCLUSIONS
  Birth by repeat CS, whether planned or unscheduled, was associated with an increased risk of hospitalisation with asthma but no difference in risk of obesity at age 5 y. Greater risk of death and learning disability following unscheduled repeat CS compared to VBAC may reflect complications during labour. Further research, including meta-analyses of studies of rarer outcomes (e.g., cerebral palsy), are needed to confirm whether such risks are similar between delivery groups.
authors.affiliation: Division of Applied Health Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Mairead
authors.initials: M
authors.lastname: Black
authors.affiliation: Division of Applied Health Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Siladitya
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Diabetes Research Unit, NHS Grampian, Aberdeen, United Kingdom.
authors.forename: Sam
authors.initials: S
authors.lastname: Philip
authors.affiliation: Tommy's Centre for Maternal and Fetal Health, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Norman
authors.affiliation: Medical Statistics Team, Division of Applied Health Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: McLernon
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D016022:Case-Control Studies; D002547:Cerebral Palsy / Q000453:epidemiology*; D017604:Cesarean Section, Repeat / Q000706:statistics & numerical data*; D046688:Child Mortality; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D016247:Information Storage and Retrieval; D007859:Learning Disabilities / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D063766:Pediatric Obesity / Q000453:epidemiology*; D011247:Pregnancy; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D047929:Term Birth; D016064:Vaginal Birth after Cesarean / Q000706:statistics & numerical data*; D055815:Young Adult