title: Research review: Birth by caesarean section and development of autism spectrum disorder and attention-deficit/hyperactivity disorder: a systematic review and meta-analysis.
abstract: BACKGROUND
  Given the growing prevalence of birth by Caesarean section (CS) worldwide, it is important to understand any long-term effects CS delivery may have on a child's development. We assessed the impact of mode of delivery on autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD).
  
  
  METHODS
  We conducted a systematic review of the literature in PubMed, Embase, CINAHL, PsycINFO and Web of Science up to 28 February 2014. No publication date, language, location or age restrictions were employed.
  
  
  RESULTS
  Thirteen studies reported an adjusted estimate for CS-ASD, producing a pooled odds ratio (OR) of 1.23 (95% CI: 1.07, 1.40). Two studies reported an adjusted estimate for CS-ADHD, producing a pooled OR of 1.07 (95% CI: 0.86, 1.33).
  
  
  CONCLUSIONS
  Delivery by CS is associated with a modest increased odds of ASD, and possibly ADHD, when compared to vaginal delivery. Although the effect may be due to residual confounding, the current and accelerating rate of CS implies that even a small increase in the odds of disorders, such as ASD or ADHD, may have a large impact on the society as a whole. This warrants further investigation.
authors.affiliation: Department of Obstetrics and Gynaecology, The Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland.
authors.forename: Eileen A
authors.initials: EA
authors.lastname: Curran
authors.forename: Sinéad M
authors.initials: SM
authors.lastname: O'Neill
authors.forename: John F
authors.initials: JF
authors.lastname: Cryan
authors.forename: Louise C
authors.initials: LC
authors.lastname: Kenny
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Dinan
authors.forename: Ali S
authors.initials: AS
authors.lastname: Khashan
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Kearney
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology*; D000067877:Autism Spectrum Disorder / Q000209:etiology*; D002585:Cesarean Section / Q000009:adverse effects*; D006801:Humans
keywords: Autism spectrum disorder; Caesarean section; attention-deficit/hyperactivity disorder