A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Fall, 2019 | Number 4, Volume 33

New research implicates prenatal acetaminophen exposure in ASD and ADHD

A new study adds to evidence of an association between prenatal exposure to acetaminophen (Tylenol) and autism spectrum disorders (ASD). In addition, the study suggests that maternal use of acetaminophen during pregnancy is associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD). 

Yuelong Ji and colleagues analyzed umbilical cord blood samples from 996 births and measured the amount of acetaminophen and two of its byproducts in each sample. The researchers found that by the time the children were around nine years of age, 25.8% were diagnosed with ADHD only, 6.6% with ASD only, and 4.2% with both ASD and ADHD. 

The researchers divided their results into three different levels of exposure. They found that compared to children with the lowest exposure, those in the middle group were 2.14 times more likely to have ASD, and those in the highest third were 3.62 times more likely to have ASD. Compared to children with the lowest exposure, those in the middle group had 2.26 times the risk for ADHD, and those with the highest exposure had 2.86 times the risk for ADHD. 

The findings follow earlier studies showing elevated rates of learning and behavior problems in children exposed prenatally to acetaminophen. In one study (see ARRI 2016, Vol. 3), Claudia Avella-Garcia and colleagues found that boys (but not girls) regularly exposed to acetaminophen in the womb had poorer scores on the Child Autism Spectrum Test (CAST) and were more likely to exhibit hyperactivity and impulsive behavior at five years of age. Earlier (see ARRI 2013, Vol. 4), Ragnhild Eek Brandlistuen and colleagues found that children exposed to prenatal acetaminophen for more than 28 days had poorer gross motor and communication skills, exhibited more behavior problems, and had higher activity levels.


“Association of cord plasma biomarkers of in utero acetaminophen exposure with risk of attention-deficit/hyperactivity disorder and autism spectrum disorder in childhood,” Yuelong Ji, Romuladus E. Azuine, Yan Zhang, Wenpin Hou, Xiumei Hong, Guoying Wang, Anne Riley, Colleen Pearson, Barry Zuckerman, and Xiaobin Wang, JAMA Psychiatry, October 30, 2019 (epub prior to print publication). Address: Xiaobin Wang, Center on the Early Life Origins of Disease, Department of Population, Family and Reproductive Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, [email protected]


 “Study suggests acetaminophen in pregnancy linked to higher risk of ADHD, autism,” Medical Xpress, October 30, 2019.