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Tylenol, Pregnancy and Autism/ADHD: A Closer Look at the Science


With the chaos erupting Tylenol (Acetaminophen) and pregnancy, I thought it would be helpful to look at the actually studies and see how they can effect your growing baby. Tylenol Autism Pregnancy


We know that navigating medical advice during pregnancy can be overwhelming--too much information, too many blogs and too many tiktoks, and it's natural to have questions about the medications you take. Tylenol, or acetaminophen, has long been considered a safe option for pain and fever, but recent studies have raised questions that many mothers-to-be are asking. Let's break down what the latest research says in an easy-to-understand way.

Tylenol Autism Pregnancy


Tylenol and Autism and ADHD
Obviously this is NOT Acetaminophen--but stock photos only go so far

How Researchers are Studying Acetaminophen's Effects Tylenol Autism Pregnancy


Scientists have been working to find new ways to test for a link between acetaminophen use and potential health outcomes in children. Here's a look at three different methods and their findings:


  • Self-Report Questionnaires (Negative Control Exposure): One study looked at over 8,800 children to see if mothers who used acetaminophen had children with a higher risk of ADHD. To control for confounding factors like genetics and lifestyle, they compared acetaminophen use during pregnancy with use four years before and after pregnancy. The study found that only use during pregnancy was associated with an elevated risk of ADHD, suggesting that the link might not be due to constant, long-term family factors.


  • Umbilical Cord Blood Biomarkers: Another study took a more direct approach by measuring acetaminophen metabolites in the umbilical cord blood of 996 newborns. This method provides an objective measure of the fetus's direct exposure to the drug. The study found a dose-dependent association, meaning that the higher the level of acetaminophen found in the cord blood, the greater the risk of an ADHD or autism spectrum disorder (ASD) diagnosis later in childhood. This finding strengthens the idea that the exposure itself is a key factor.


  • Meconium Biomarkers: A third study also used a direct measurement, analyzing acetaminophen in the babies' meconium (first poop) to assess exposure during the second and third trimesters. This research found an association between prenatal acetaminophen exposure and a decreased birth weight of approximately 136 grams. It also found a 20% increased weekly hazard of delivery, suggesting a higher likelihood for an earlier birth. This study also noted a significant finding for mothers and doctors to consider: the average gestational age for those exposed to acetaminophen was 39 weeks, compared to 39.3 weeks for those who were not.


The Challenge of Conflicting Data: A Sibling Study

Tylenol Autism Pregnancy

Not all studies have reached the same conclusion. One large sibling-control study of over 26,000 children showed that while long-term acetaminophen use (29 days or more) was associated with an increased risk of ADHD, this link disappeared when comparing siblings where one was exposed and the other was not. This suggests that the association may be due to shared familial factors, like genetics, rather than the drug itself.

It's important to understand the limitations of this type of study: it relied on self-reported questionnaires given to mothers at 17 weeks, 30 weeks, and 6 months postpartum. This method might not capture the full picture of a mother's medication use. The study also used Norwegian Patient Registry data (NPR) to identify ADHD diagnoses. This means that if a diagnosis was not properly reported or was misreported, it wouldn't be included in the data, which could affect the study's conclusions.


Important Takeaways for Mothers and Doctors


A key theme in the research is that while there's a correlation between acetaminophen exposure and certain neurodevelopmental and birth outcomes, studies often don't address the reason a woman took the medication in the first place. Was it for a headache, or was it to treat a high fever or an infection? These underlying conditions could be a confounding factor.


Ultimately, the goal is for you and your doctor to have all the information necessary to make a thoughtful, personalized decision about your health. The difference of just over two days in average gestation found in one study may be a significant factor in your personal risk assessment, depending on your specific circumstances e.g. if you're already high-risk, 2-3 days can make a difference.


Therefore, the consensus among many experts in these studies (not Eos Health--we're therapists) is to limit usage to only when necessary. This may look different for different women, I would discuss concerns and risk factors with your OB/GYN and providers.



If you're curious how this connects to the recent announcement that there may be a treatment for certain types of autism; I will write a follow up blog soon on what that means, who may it affect and how it connects to this research.


References


  • Bauer, A. Z., Swan, S. H., Kriebel, D., Liew, Z., Taylor, H. S., Bornehag, C. G., Andrade, A. M., Olsen, J., Jensen, R. H., Skakkebaek, N. E., Jégou, B., & Kristensen, D. M. (2021). Paracetamol use during pregnancy — a call for precautionary action. Nature Reviews Endocrinology, 17(12), 757–766. https://doi.org/10.1038/s41574-021-00553-7

  • Baker, B. H., Burris, H. H., Bloomquist, T. R., Boivin, A., Gillet, V., Larouche, A., Takser, L., Bellenger, J. P., Pasquier, J. C., & Baccarelli, A. A. (2022). Association of Prenatal Acetaminophen Exposure Measured in Meconium With Adverse Birth Outcomes in a Canadian Birth Cohort. Frontiers in Pediatrics, 10, 828089. https://doi.org/10.3389/fped.2022.828089

  • Gustavson, K., Ystrom, E., Ask, H., Torvik, F. A., Hornig, M., Susser, E., Lipkin, W. I., Lupattelli, A., Stoltenberg, C., Magnus, P., Mjaaland, S., Askeland, R. B., Walle, K. M., Bresnahan, M., Nordeng, H., & Reichborn-Kjennerud, T. (2021). Acetaminophen use during pregnancy and offspring attention deficit hyperactivity disorder – a longitudinal sibling control study. JCPP Advances, 1(2), e12020. https://doi.org/10.1002/jcv2.12020


  • Ji, Y., Azuine, R. E., Zhang, Y., Hou, W., Hong, X., Wang, G., Riley, A., Pearson, C., Zuckerman, B., & Wang, X. (2020). 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, 77(2), 180–189. https://doi.org/10.1001/jamapsychiatry.2019.3259

  • Liew, Z., Kioumourtzoglou, M. A., Roberts, A. L., O’Reilly, E. J., Ascherio, A., & Weisskopf, M. G. (2019). Use of Negative Control Exposure Analysis to Evaluate Confounding: An Example of Acetaminophen Exposure and Attention-Deficit/Hyperactivity Disorder in Nurses’ Health Study II. American Journal of Epidemiology, 188(4), 768–775. https://doi.org/10.1093/aje/kwy288




 
 
 

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