Recently, murmurs began about one specific assertion that Health and Human Services Secretary Robert F. Kennedy Jr. would make in a soon-to-be-released report from the HHS. Kennedy, founder of the “Make America Healthy Again” movement and whose opinions are often born of pseudoscience and its online peddlers, has long been a vocal critic of vaccines (as was abundantly clear in his Senate hearing) and will now suggest, accordingly to reporting by the Wall Street Journal, that use of the common pain reliever acetaminophen during pregnancy is linked to autism. An assertion rejected by all major organizations overseeing maternal health guidance, and one unsupported by definitive scientific research.

Acetaminophen is a widely-used and relied-upon standalone medication (aka, Tylenol in the US and paracetamol abroad) during both pregnancy and not, that is also present in various cold and flu formulations. “It’s really one of the few medications we have to relieve pain and fever during pregnancy,” says Rachel Blake, MD, an OBGYN at Beth Israel in Boston and a clinical instructor at Harvard Medical School. It’s the preferred option because alternatives like NSAIDs (like ibuprofen or Aleve) can be harmful, potentially causing kidney problems leading to low amniotic fluid and cardiac issues, especially beyond the late second trimester, explains Lucky Sekhon, MD, a double board-certified reproductive endocrinologist and enfertility specialist and OBGYN at RMA of New York and author of the fertility guide The Lucky Egg. The recommended dosage is the same for both pregnant people and adults (325 to 600 mg every four to six hours, not to exceed 3,000 mg a day), and it’s suggested by doctors to take the lowest effective amount for the shortest duration of time to find relief.

The theory that prenatal acetaminophen exposure could correlate with increased risk of autism and ADHD, currently being hawked by RFK Jr., can be traced back to smaller observational studies (including NIH-funded research) and a more recent review of 46 epidemiological studies that found 27 reported positive correlations, says Sekhon. But, crucially, correlation does not equal causation, a point that’s driven home frequently not just by doctors and medical researchers, but also data scientists and economists (like Emily Oster, for one). The example frequently cited as an explainer is that while there’s a strong correlation between ice cream sales and shark attacks (they both go up in the summertime months), one doesn’t cause another. The largest and best-designed relevant study to date has been out of Sweden, which looked at prenatal acetaminophen and neurodevelopmental disorders in 2.5 million children. “No correlation was found after controlling for key confounding factors like genetics and familial environment,” says Sekhon, adding re-analysis of the data comparing siblings from the same household who were exposed versus not exposed in utero led to the correlation no longer being seen.

Many of the studies currently used are observational, says Sekkon. This means they rely on women recalling the past and the behaviors they engaged in or what they ate while pregnant, which can contribute to inaccuracy and bias in the results. “One of the toughest parts of the field of obstetrics is the lack of data,” says Blake. That’s because while we now require women to be included in trials (they were banned from them for years until FDA guidance changed in 1993), pregnant women remain largely excluded due to ethical concerns about fetal harm, says Abigail Bertelson, founder of Zenith Health, a new digital platform offering pregnant women access to clear, data-driven answers. “This has left us with substantial gaps in understanding of various medications during pregnancy,” says Bertelson, adding that what we need are large-scale prospective studies that follow thousands of women from early pregnancy through children’s development, collecting detailed data (medication, demographics, medical history, genetics) along the way. Something that, in the current political climate where cuts to research funding, particularly related to women’s health, are ever more frequent, feels impossible. “The irony is that sometimes the harm of not having safe, evidence-based treatments available during pregnancy can be greater than the risk of inclusion in research,” Bertelson adds.