Fever itself can endanger fetal development, which is why Tylenol remains an important tool for protecting moms and babies.
Primum non nocere. First do no harm. This instruction, admonition and promise rings in the ears of every graduating medical student. The promise to not only help, but also not harm, our patients keeps physicians awake at night.
Nowhere else is this more poignant than in the OB-GYN‘s office. Despite only one name on the schedule at every pregnancy appointment, two patients are seen. The delicate balance between mother and baby occupies every decision, even when their needs are in direct opposition. Medical care of a pregnant mother is already severely limited by the needs of the future child, restricting available testing, medications and procedures. The question of risk versus benefit influences every decision in care, most often favoring the baby. Unfortunately, this frequently neglects the patient whose name is on the schedule.
This influence applies even to the most seemingly innocuous medications available, including Tylenol.
Performing good quality studies on women of reproductive age, much less pregnant women, is incredibly difficult due to the ethical concerns inherent in such a study. The gold standard of research—a double-blind, placebo-controlled experiment—cannot be ethically completed. As a result, we rely on lesser quality studies, with all of their intrinsic flaws. Even though those studies may not be of the highest scientific quality, they don’t change the imperative: You have to treat pain in women. You have to treat pain in pregnancy.
Unfortunately, a study’s flaws and nuances are very difficult to communicate to the world at large. The black-and-white and result of “good” or “bad” overwhelms the many shades of gray that occur in medical care. A study that “suggests strong evidence of a likely relationship between Tylenol and neurodevelopmental disorders” (Prada, 2025) such as autism or ADHD is exactly that: a suggestion. Dosing, duration, timing of exposure and the underlying reason why the Tylenol was needed at all are potential strong influences on the final outcome.
One of the most common reasons for Tylenol—fever—poses significant risk for both the woman and her baby if untreated. High fevers may impact growth and development. The deep discomfort experienced during a fever is also associated with lethargy, decreased liquid and food intake, and an inability to function normally, impacting both mother and baby. The underlying infection causing the fever also poses a risk because so many viruses and bacteria threaten safe fetal development. An untreated infection may lead to more dire circumstances for the woman, threatening both her survival and the baby’s.
Even more than the details of medication exposure, the magnitude of impact must be evaluated. A difference of 1.3 percent versus 1.5 percent means two additional people out of 1,000 will be affected. It also means that withholding the medication delays or denies much-needed care to the other 998 women.
Pregnant women as a general rule do not take medication unless it is indicated, such as treatment of fever, pain or other inflammation. While a slight increase in risk of a neurodevelopmental disorder cannot be ignored, women and their physicians deserve the right to give and receive appropriate medical care. This care should be given with explanation for the nuanced findings of studies, and without judgment by anyone outside the exam room. In medicine, the goal is to treat the patient—that means every patient, moms included.
