Study finds no link between newborn circumcision and autism risk

In a cohort of nearly 3,000 boys followed from birth into childhood, young boys who were circumcised just after birth did not have a higher risk of autism, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.

Two observational studies published over a decade ago-one in 2013, another in 2015-suggested a possible circumcision-autism link. Media coverage following comments by administration officials last year resurfaced the earlier research.

The new study, published online August 3 in JAMA Pediatrics, examined data from a nation-wide ongoing child health study known as the ECHO (Environmental influences on Child Health Outcomes) Cohort study. The analysis found no link between circumcision and autism: Boys circumcised just after birth did not have a higher risk of autism compared to uncircumcised boys in the cohort.

"Parents have been concerned about this potential circumcision-autism connection, but hopefully these findings may help allay their fears," says senior author Monica McGrath, ScD, MHS, research professor in the Bloomberg School's Department of Epidemiology and director of the Environmental influences on Child Health Outcomes Data Analysis Center, also at the Bloomberg School.

Circumcision rates have been declining in the U.S. At the same time, the number of autism diagnoses in children in the U.S. has increased dramatically in recent decades. According to Centers for Disease Control and Prevention reports, roughly one child in 150 had an autism diagnosis in 2000, but as of 2022 the CDC reported a prevalence of one child in 31 among 8-year-olds. It's not clear whether there has been an actual increase in autism prevalence or if the higher numbers reflect more awareness, more testing, and subsequent diagnoses.

Public discussion last year around a possible circumcision-autism link prompted McGrath and her colleagues in the ECHO Cohort study to perform their own analysis.

"We knew we had the data to help investigate this question," McGrath says.

The analysis included 2,771 boys who had been enrolled at 14 different ECHO sites across the U.S. About 66% (1,840) were circumcised before maternity hospital discharge, and about 7% (192) had a documented or parent-reported autism diagnosis at a mean age of 3.8 years.

Among the boys with neonatal circumcision, the risk of autism diagnosis was 6% (108/1,840). The autism risk among uncircumcised boys was higher at 9% (84/931), and after adjusting for likely confounding factors such as parental age and family history of autism, there was no significant association.

The researchers also looked at acetaminophen exposure in the neonatal period. It was too uncommon (<5%) to permit analysis of its potential association with autism.

"We observed no association between circumcision and autism in boys, but it remains important to evaluate the safety of common medical procedures," McGrath says.

She and her ECHO study colleagues are continuing to evaluate other factors that may explain the rise in autism diagnoses.