Circumcision of males was associated with a 2-fold increase in the risk for early-onset (infantile) ASD in Danish children born from 1994 to 2003. Further, a study of US males (56% of participants born from 1982 to 1996, when acetaminophen use in infants would likely have been favored over aspirin) identified social problems associated with circumcision. APAP is sometimes used as an analgesic following circumcision despite the fact that such use is of highly questionable effectiveness. However, administration of APAP by physicians and by parents following infant circumcision has not been widely documented.

a. Epidemiology (pregnancy): Use of APAP during pregnancy has been associated with adverse long-term effects on the mental health of offspring in numerous studies.

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b. Epidemiology (childhood): Analysis of the Danish National Birth Cohort (DNBC) by Alemany and colleagues revealed an odds ratio (OR) of 1.3 (CI 1.02–1.66) for ASD associated with postnatal APAP exposure, despite the fact that the use of APAP appears to be dramatically underreported in the DNBC.

Regression: APAP use during early childhood is associated with a 20-fold greater risk of regressive ASD. APAP use with mild adverse reactions to a vaccine, but not mild adverse reactions to a vaccine alone, is associated with ASD.

Higher levels of APAP in cord blood are associated with ASD.

Ultra-Orthodox Jews in Israel have a reported prevalence of ASD less than half of that of reform Jews. Traditional circumcision practices employed by Ultra-Orthodox Jews do not utilize APAP. Further, Orthodox Jews may use less pain medications during childbirth than others.