In-Utero Acetaminophen Exposure May Increase Risk for ADHD and Autism
Newborns exposed to high levels of acetaminophen in the womb were three times more likely to be diagnosed with ADHD or autism spectrum disorder, according to a new controversial Johns Hopkins study. The findings, which warrant additional investigation and do not prove causality, have received backlash from members of the professional community who point out inconsistencies in the selection of sampled children and the method used to determine acetaminophen exposure.
November 21, 2019
Cord plasma biomarkers of fetal exposure to acetaminophen — the generic name for the drug Tylenol — were associated with significantly increased risk of childhood attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), according to a study published last month in JAMA Psychiatry.1
Researchers studied 996 mother-infant dyads from the Boston Birth Cohort, a 20-year-long study that looked at early-life factors impacting pregnancy and child development. Umbilical cord blood samples were taken at birth, and then researchers divided participants into three groups according to the amount of acetaminophen and its metabolites present in blood samples. Those with the highest levels of exposure had 2.86 times the risk for ADHD and 3.62 times the risk for autism, compared to those with the lowest exposure.
However, Melbourne fertility specialist Joseph Sgroi cautions that “causation has not been established,” and that studies such as this one “do little to decrease the anxiety that comes with being pregnant, undergoing childbirth, and raising a child.”2
In addition, the cord plasma biomarkers used to gauge acetaminophen exposure do not necessarily reflect a greater frequency of acetaminophen use by mothers and may, instead, indicate use of the medication immediately prior to the child’s birth. Acetaminophen is commonly administered during labor for pain relief.
Dr Alex Polyakov, a senior lecturer in the Department of Obstetrics and Gynecology at The University of Melbourne says that this was not a truly prospective study since “Cord blood samples were collected at the time of birth, and some, but not all, children were followed up with neurodevelopmental testing for a number of years.” Additionally, significant selection bias occurred since, “Only those children who had neurodevelopmental testing, which was not routine for the whole cohort, were included in the analysis.”3 Though the findings of this study are notable, they warrant further investigation.
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1 Ji Y, Azuine RE, Zhang Y, et al. Association of Cord Plasma Biomarkers of In Utero Acetaminophen Exposure With Risk of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder in Childhood. JAMA Psychiatry. (Oct. 2019) https://doi.org/10.1001/jamapsychiatry.2019.3259
2 Haggan, Megan. Paracetamol in Pregnancy: ADHD, Autism Link? AJP.com.au. (May 2019) https://ajp.com.au/news/paracetamol-in-pregnancy-adhd-autism-link/
3 Haggan, Megan. Paracetamol in Pregnancy: ADHD, Autism Link? AJP.com.au. (May 2019) https://ajp.com.au/news/paracetamol-in-pregnancy-adhd-autism-link/