In Reply We published a study on mode of delivery, more specifically birth by cesarean section (CS), and the development of autism spectrum disorder (ASD).1 In it, we found that CS was associated with ASD in the population. However, the association was attenuated when we used a sibling design, and we concluded that CS was likely not a cause of ASD and a more probable explanation of the association was confounding.
Curran EA, Kenny LC, Khashan AS. Sibling Comparisons and Confounding in Autism Epidemiological Studies—Reply. JAMA Psychiatry. 2016;73(3):303. doi:10.1001/jamapsychiatry.2015.2882