Ritual circumcision and risk of autism spectrum disorder in 0- to 9-year-old boys: national cohort study in Denmark Morten Frisch et al. A total of 342,877 boys born between 1994 and 2003 and followed in the age span 0–9 years between 1994 and 2013. "Conclusions We confirmed our hypothesis that boys who undergo ritual circumcision may run a greater risk of developing ASD. This finding, and the unexpected observation of an increased risk of hyperactivity disorder among circumcised boys in non-Muslim families, need attention, particularly because data limitations most likely rendered our HR estimates conservative." "Until recently, it was believed that newborns are incapable of interpreting noxious stimuli in a manner comparable to that of older children and adults. This idea has now been abandoned with almost universal consensus that newborns and infants perceive pain and stress very much like older children and adults. In a study of 5-, 12- and 15-month-old infants, Kouider et al.3 showed that even the youngest infants had full capacity for conscious perception, although their ability to express such perceptions had not yet developed. Also, animal studies and clinical investigations strongly suggest that neonatal pain has an impact on subsequent responses to stress and anxiety later in life." "With a total of 4986 ASD cases, our study showed that regardless of cultural background circumcised boys were more likely than intact boys to develop ASD before age 10 years (HR = 1.46; 95% CI: 1.11–1.93). Risk was particularly high for infantile autism before age five years (HR = 2.06; 95% CI: 1.36–3.13). Circumcised boys in non-Muslim families were also more likely to develop hyperkinetic disorder (HR = 1.81; 95% CI: 1.11–2.96). Associations with asthma were consistently inconspicuous (HR = 0.96; 95% CI: 0.84–1.10)."