Copyright Newsweek
A new study of existing research has concluded there is no clear link between Tylenol use during pregnancy and the risk of a baby developing autism or attention deficit/hyperactivity disorder (ADHD). "Existing evidence does not clearly link maternal paracetamol use during pregnancy with autism or ADHD in offspring," the study authors wrote. They added that "regulatory bodies, clinicians, pregnant women, parents, and those affected by autism and ADHD should be informed about the poor quality of the existing reviews and the likelihood that positive associations reported in studies were driven by familial confounding." "The work highlights the need for investment in women’s health research, particularly on medications in pregnancy," Shakila Thangaratinam, author of the study and a professor of women's health at the University of Liverpool, England, told Newsweek. Newsweek has contacted the Department of Health and Human Services via email for comment. Why It Matters In light of the Trump administration's assertion earlier this year that the use of acetaminophen, widely known as Tylenol, by pregnant mothers could be the "answer to autism," research and debate around the use of the painkiller during pregnancy has become a heated topic of contention. While President Donald Trump warned against the use of the drug in pregnancy, experts said the link remains unproven, and some argued the president’s messaging was not only "harmful," but also not backed by "the full body of scientific evidence." The announcement also sparked public backlash and pregnant women began posting videos of themselves taking Tylenol on social media following the president's announcement, saying they would not follow the advice. What To Know While not being new research per se, the study synthesizes previous reviews on the topic that have been published, evaluating the totality of evidence despite not being a new empirical study, David Savitz, a professor of epidemiology, and of obstetrics, gynecology and pediatrics at Brown University, Rhode Island, told Newsweek. The study, published in the British Medical Journal (BMJ) on November 10, evaluated the results from nine reviews that reported the findings of 40 different primary studies. Of the studies evaluated, six reported on autism and 17 on ADHD. All of the nine reviews reported "a positive association" between maternal paracetamol use in pregnancy and adverse neurodevelopmental outcomes in offspring. However, the authors wrote that "the methodological quality of the nine included systematic reviews revealed substantial weaknesses across several critical domains," they did not provide "comprehensive literature search strategies" and did not present "a list of excluded studies with justifications." They also noted that consideration and assessment of potential bias in primary studies was "frequently absent or partially present." They added that this risk of bias in the primary studies were considered in some cases to "influence their results." Seven of the nine reviews warned against determining there is a link between maternal paracetamol use and autism or ADHD, or both in offspring, citing "lack of data, bias in the primary studies, and unmeasured or inadequately controlled confounders." The authors wrote: "Few reviews accounted for the study quality, appropriate control of relevant confounders, and rigorous ascertainment of drug use and outcomes in the primary studies when interpreting the evidence." This finding prompted them to conclude there is a "lack of robust evidence linking paracetamol use in pregnancy and autism and ADHD in offspring." When asked if he was surprised about the conclusion of the study, Savitz said he was not, "given how inconsistent and ultimately unconvincing the studies on this topic have been." "From my assessment, the weight of evidence points away from an association between Tylenol and neurodevelopmental disorders given a series of recent high quality studies that document an absence of effect," he added. He said that the studies have used sibling controls, meaning that they compared pregnancies of the same mother when that mother was and was not exposed to Tylenol. These results provide "consistent evidence of a lack of increased risk in the child who was exposed during pregnancy," he said. "Only with a very selective and in my view, generous, interpretation of the literature would the conclusion be that Tylenol causes autism or ADHD," Savitz said. What People Are Saying The study authors wrote: "Given that alternative classes of drugs for relief of pain and fever, such as non-steroidal anti-inflammatory drugs, are known to adversely affect the fetal vascular system and can cause complications such as oligohydramnios and premature closure of the ductus arteriosus, and considering the harmful effects of pyrexia on pregnancy, women should be advised to take paracetamol when needed to treat pain and pyrexia in pregnancy." Shakila Thangaratinam, author of the study and a professor of women's health at the University of Liverpool, England, told Newsweek: "Regulatory agencies worldwide have consistently reassured on the safety of paracetamol in pregnancy. Our work collates all the available evidence in a systematic, methodologically sound manner, to help health care professionals and women and families make informed decisions as there is no clear link between mothers’ taking paracetamol in pregnancy and children diagnosed with autism or ADHD." She added: "Pregnant women should take paracetamol if indicated in pregnancy. It is likely that autism or ADHD in children is driven by shared familial genetic and environmental factors and unmeasured confounders, and not exposure to paracetamol. So women should not feel guilty that their actions have somehow affected their babies." David A. Savitz, a professor of epidemiology, and of obstetrics, gynecology and pediatrics at Brown University, Rhode Island, told Newsweek: "I would have particular concern for women who have faced the challenges of having a child with autism or ADHD and are now being told that a commonly used medication may be the cause of it despite the lack of evidence that this is the case. For them, this is not an academic exercise but a very personal consideration for them and their family, and the implication that if they had just "toughed it out" and suffered with fever, pain, or other indications for the use of Tylenol they would have prevented developmental problems in their child—despite fever itself being a very plausible cause of harm to the developing fetus. Offering hypotheses is the way that science moves forward, but it's extremely important to be clear on whether there is a basis for further research, which there is regarding Tylenol and any other medication taken during pregnancy, versus a proven or strongly suspected determinant of a health outcome, which is not the case for Tylenol." What Happens Next The study determined the current evidence on this topic is "insufficient to definitively link in utero exposure to paracetamol with autism and ADHD in childhood," suggesting that more research needs to be done before any such associations can be determined.
