Delivery by cesarean section (CS) is associated with a 20% increase in risk of autism diagnosis; however, researchers believe the association is attributed to familial confounding by genetic and environmental factors.
Christina Dalman, PhD, MD, of the Karolinksa Institutet in Stockholm, Sweden, and colleagues identified perinatal factors and autism spectrum disorder (ASD) diagnoses from the Swedish Medical Birth Register and Swedish National Patient Register to determine the effects of mode of delivery on ASD. The cohort consisted of 2,697,315 children and 28,290 cases of ASD. A follow-up sibling design study included 13,411 sibling pairs.
The researchers found that elective CS (hazard ratio, 1.21; 95% CI, 1.15-1.27) and emergency CS (hazard ratio, 1.15; 95% CI, 1.10-1.20) was associated with ASD compared to unassisted vaginal delivery (VD), however in the sibling control analysis, elective CS was not associated with ASD in partially (odds ratio [OR], 0.97; 95% CI, 0.85-1.11) or fully (OR, 0.89; 95% CI, 0.76-1.04) adjusted models. Emergency CS was significantly associated with ASD in partially adjusted analysis (OR, 1.20; 95% CI, 1.06-1.36), but was not seen in the fully adjusted model (OR, 0.97; 95% CI, 0.85-1.11).
"The overall risk of ASD is very small, and this most recent work suggests that most, if not all, the risk is not to do with the cesarean section at all, which is reassuring for parents," Louise Kenny, PhD, consultant obstetrician and gynecologist at Cork University Maternity Hospital, who worked on both studies, told Medscape Medical News.
Because the rates of cesarean section (CS) are increasing worldwide, it is becoming increasingly important to understand the long-term effects that mode of delivery may have on child development.
The purpose of the study was to investigate the association between obstetric mode of delivery and autism spectrum disorder (ASD). Perinatal factors and ASD diagnoses based on the International Classification of Diseases, Ninth Revision (ICD-9),and the International Statistical Classification of Diseases, 10th Revision (ICD-10),were identified from the Swedish Medical Birth Register and the Swedish National Patient Register.