A large U.S. study published in JAMA Pediatrics has found no evidence that newborn circumcision increases the risk of autism in boys, offering reassurance to parents considering the procedure or whose sons were circumcised. The research was led by Monica McGrath, a research professor at Johns Hopkins Bloomberg School of Public Health, and analysed data from a national health initiative tracking child health outcomes.
Neonatal circumcision and autism: no link found in large US study
Autism spectrum disorder is a neurodevelopmental condition characterised by differences in social interaction and communication, with common features including repetitive behaviours and unusual responses to sensory input. Diagnosis relies on clinical assessments of a child’s development and behaviour.
Over recent decades the recorded rate of autism diagnoses has risen, with official estimates showing a substantial increase from 2000 to 2022. While experts continue to debate how much of the rise reflects a real increase versus improved awareness and screening, the trend has driven research into potential environmental influences that might interact with genetic predispositions.
Among the early-life exposures examined is neonatal medical circumcision, a common surgical procedure removing the foreskin shortly after birth. In the United States, about half of newborn boys undergo circumcision in hospital settings, though the share has been decreasing in recent years. The study sought to determine whether this widely performed procedure could be linked to later autism.
The Johns Hopkins-led team used data from the Environmental Influences on Child Health Outcomes project, analysing 2,771 male children from 14 U.S. sites. All were singleton births, and when families had several participating children, one was randomly chosen to avoid shared-family bias.
Researchers reviewed medical records to establish whether circumcision occurred at a hospital within 28 days of birth, then tracked autism diagnoses, defined by parental reports of a professional diagnosis or standard clinical assessments. The average age of autism diagnosis in the cohort was just under four years old.
In addition to formal diagnoses, the study employed two parent-completed screening tools: the Social Responsiveness Scale (used for 1,886 children) and the Child Behavior Checklist (used for 1,880 children), aimed at identifying social impairments and broader behavioural concerns linked to autism.
Of the 2,771 boys, 1,840 (66 per cent) were circumcised during their hospital stay, while 931 (34 per cent) were not. Overall, 192 children were diagnosed with autism, about seven per cent of the sample. When broken down by circumcision status, 6 per cent of circumcised boys and 9 per cent of uncircumcised boys were diagnosed.
However, after adjusting for factors that could influence both circumcision and autism diagnosis—such as maternal education, geographic region, family history of autism and parental age—the difference between groups was no longer statistically meaningful. The parent-reported questionnaires yielded a similar pattern, with no clear link between circumcision and higher scores on the measures of autism-related traits.
The study noted one regional exception: among children born in the Western United States, circumcised boys appeared more likely to score in the elevated range on one questionnaire. The researchers described this as likely a statistical fluke given the number of comparisons and the finding being driven by a single site.
Pain management data were available for fewer than half of the circumcised infants. Among those, only 4 per cent received acetaminophen during the procedure and around 7 per cent received it within 30 days of birth. Most infants received alternatives such as a nerve block or a sugar solution, and some received more than one form of pain relief. Because acetaminophen use was so rare, the researchers could not directly test its role in any potential pathway to autism, but they concluded that such a pathway is unlikely.
“Parents have been concerned about this potential circumcision-autism connection, but hopefully these findings may help allay their fears,” McGrath said in a Johns Hopkins news release. She added that the study confirms no association between circumcision and autism in boys, while stressing the importance of ongoing evaluation of the safety of common medical procedures.
The researchers also acknowledged limitations. They had limited information on participants’ health insurance status, which can influence both a family’s decision to have a hospital circumcision and access to developmental evaluations. The study focused on hospital-based, early-life circumcisions, so the results may not apply to later or non-hospital circumcisions. Acetaminophen dosing data reflected hospital records only, excluding any at-home use after discharge. Additionally, while the parent-reported tools are validated screening instruments, they are not diagnostic in themselves. Although the cohort spanned multiple sites, it does not perfectly represent all American male newborns.
“We observed no association between circumcision and autism in boys, but it remains important to evaluate the safety of common medical procedures,” McGrath said. The team is continuing to explore other potential explanations for the rise in autism diagnoses.
The study, Neonatal Medical Male Circumcision and Child Autism Diagnosis, was authored by Monica McGrath and colleagues, including Xiuhong Li, Lisa P. Jacobson, Bennett Leventhal, Judy L. Aschner, Brennan Baker, Karla Cardoso Garcia, Aisha S. Dickerson, Amy J. Elliott, Jody Ganiban, Amanda Goodrich, Daniel B. Horton, Melinda Jarnecke, Sarah Keim, Brian K. Lee, Courtney D. Lynch, Mark Klebanoff, Abdul-Manaf Mutaru, Ruby H. N. Nguyen, Rebecca J. Schmidt, Hyeong-Moo Shin, Lauren C. Shuffrey, Jonathan L. Slaughter, Annemarie Stroustrup, Zhaozhong Zhu, Aaron A. R. Tobian, and M. Kate Grabowski.
