• Autism spectrum disorder;
  • attention-deficit/hyperactivity disorder;
  • Caesarean section


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).


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.


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).


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.