Behind Trump’s Tylenol Warning: A Lack Of Data On How Drugs Affect Pregnant Women

The uproar over the Trump administration’s efforts to discourage pregnant women from taking Tylenol is highlighting a bigger problem: There has never been adequate data on the safety and effectiveness of many drugs during pregnancy, and that data became even harder to gather after the fall of Roe v. Wade.

Medical experts and women’s health advocates warn that state abortion bans are exacerbating longstanding barriers to including women of reproductive age in drug trials and other health studies, as both scientists and participating women could face new legal consequences if a drug harms a fetus. And without good information about how drugs affect pregnant women, it’s harder to navigate a morass of conflicting messages from the government and medical groups on the safety of everything from painkillers to antidepressants to vaccines.

Trump administration health officials have pledged “gold-standard science” aimed at testing whether pharmaceutical drugs are safe to take during pregnancy or whether they carry risks to fetuses’ neurological development. HHS spokesperson Andrew Nixon said the president’s recent warnings about Tylenol and autism, for instance, stem from a “commitment…to follow the science and share critical public health information as soon as it becomes available, ensuring families are informed and communities are protected.”

Yet emerging data suggests that kind of scientific evidence is becoming more difficult to obtain in much of the U.S., since women of reproductive age are more hesitant to enroll in studies in states with abortion bans. PRESTO, a federally-funded, non-partisan online database where people attempting to conceive share data with researchers, saw a more than 27 percent drop in participation in states that banned the procedure in the immediate aftermath of Dobbs, the 2022 Supreme Court ruling that overturned Roe v. Wade. There was no change in states with abortion protections.

“In the post-Dobbs era, research with pregnant people is even harder and even more difficult ethically and legally, because of concerns about causing any sort of harm to the fetus could implicate potentially fetal personhood laws or abortion laws,” said Allison Whelan, a bioethicist at Georgia State University College of Law who focuses on pregnancy.

A dozen states have banned abortion at any point in pregnancy since the fall of Roe, while 10 more have bans that kick in somewhere before the point of fetal viability, typically around 22 to 24 weeks. Some of those laws were enacted decades or even more than a century ago — before women could vote and before ultrasounds were invented — while others were passed in the leadup to the Dobbs ruling or shortly after. Lawmakers pushing the policies expressed a desire to protect both fetuses and their mothers, who they argue are often coerced into terminating pregnancies.

Some of those same red state lawmakers amended their bans over the last year after seeing what they characterized as unintended consequences, such as a rise in sepsis and hemorrhaging during delivery documented in Texas. But while they added new carveouts for threats to the health of the mother, they largely blocked bills that would have added exceptions for fetal anomalies, arguing that diagnoses can be wrong and that even if there’s a slim chance of a healthy birth, patients should take it.

That means that in 10 states where abortion is prohibited, women whose fetuses develop birth defects — whether they’re the result of a genetic mutation or exposure to pharmaceuticals — must travel out of state or carry to term a fetus likely to die shortly after birth.

Those policies are complicating the nation’s system for testing new medications.

Researchers note that the ethical guidelines shaping most research today were drafted by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research in 1974 — the year after Roe legalized abortion nationwide. And according to longstanding guidance for research ethics from the World Health Organization, any research involving pregnant women that has the potential for harm to the fetus, including all trials of new drugs, “should be conducted only in settings where women can be guaranteed access to a safe, timely and legal abortion in the event that participation in the research makes the pregnancy unwanted.”

When it comes to research protocols, the country’s current post-Dobbs patchwork of abortion restrictions is uncharted territory, with a heightened risk of participation for both scientists and women who could become pregnant.

A 2024 report by the National Academies of Sciences, Engineering and Medicine — which advises the federal government on how to best support research and use its findings — acknowledged that “fear of liability is a regularly cited obstacle” to enrolling pregnant women in medical studies. Though the authors couldn’t find any examples of a trial participant or her family suing over harm to her fetus as a result of a medication, they noted that Dobbs “is likely to increase liability for including pregnant women in clinical research” and “contributed to creating a climate of uncertainty.”

“In some states, it may be inappropriate to do some types of research involving pregnant women because the potential legal risks for pregnant women (and potentially their health care providers) are too high,” the academies cautioned.

Many clinical trials — even those that have nothing to do with reproductive health — require female participants to take regular pregnancy tests so that they can know as early as possible about any risk from the new medication to a developing fetus and drop out of the study if needed. Some trials also require reports of “adverse pregnancy outcomes” like miscarriages, stillbirths or birth defects in their published findings.

After Dobbs, some scientists worry that information — which is not shielded by federal privacy protections covering medical records — could be subpoenaed and used in a prosecution. Several state bans also threaten felony charges for anyone who assists a patient in obtaining an abortion, a vaguely defined crime that scientists worry could be leveled against them merely for learning about a trial participant’s pregnancy and talking through their options with them.

The FDA put out draft guidance this summer urging researchers to prioritize including pregnant and lactating women in medical research and suggesting ways to minimize risks. The document, however, includes no mention of abortion access varying from state to state and offers no suggestions on how researchers can protect themselves or their subjects from potential investigation or prosecution, leaving the scientific community on edge.

“If you're a researcher, and you are conducting research with people seeking abortion care, even people seeking maternal health care, and you provide them with details about abortion services, are you aiding and abetting that person?” wondered Julia Strasser, a professor at the Milken Institute School of Public Health at George Washington University who studies reproductive health. “There's a lot of confusion. There's a lot of fear.”

The FDA did not respond to a request for comment.

Further fueling researchers’ anxiety, many states have “chemical endangerment” laws that some officials have used in recent years to prosecute people who use drugs while pregnant — including prescription drugs. A New York Times investigation found that between 2016 and 2023, thousands of mothers were reported to state officials for taking antidepressants, anxiety and ADHD medications, medication to treat addiction, and even over-the-counter cold medicine.

According to a September report by the advocacy group Pregnancy Justice, nearly 400 charges were brought against women in 16 states for substance use during pregnancy between 2022 and 2024. And in some places that most aggressively enforce such laws, including Alabama, the state does not need to prove any harm to the fetus in order to secure a conviction. The state’s attorney general, Steve Marshall, has long defended the policy as an effective way to deter women from abusing drugs, arguing that the threat of incarceration encourages those struggling with addiction to seek treatment.

Yet the national academies warned the policy could also deter research, and “could pose an increased risk for some pregnant participants” taking part in drug trials.

“If you are pregnant and involved in clinical research, you are essentially intentionally taking an investigational drug that could potentially have a negative outcome to the fetus, including a spontaneous abortion,” said Whelan. “That could potentially implicate you in a state that uses a very broad interpretation of their abortion law.”

With the post-Dobbs rise in states considering “personhood” laws granting legal rights to fetuses — such as the one already on the books in Alabama that led to a temporary suspension of IVF services in the state last year — researchers worry that merely learning about a study participant’s abortion or knowing about their consumption of certain medications could force them to act as mandatory reporters of child abuse.

“What would it mean if someone had a pregnancy test that was positive at one visit and then negative the next visit and they didn’t have a baby to show for it?” asked Johns Hopkins bioethicist Jeremy Sugarman. One scenario that concerns him: the patient or the scientist could be pressured to prove that there was a miscarriage rather than an abortion. Another: that a research participant who had an abortion would misreport it as a miscarriage to the researchers out of fear of prosecution, leading to inaccurate data.

Yet anti-abortion activists defending state restrictions on the procedure note that the exclusion of women of reproductive age from medical research is much older than Dobbs. Women have long been left out of tests of experimental drugs, due in part to fears they might cause birth defects. That has meant drugs’ side effects on pregnant people and their fetuses are often discovered in the real world rather than in a controlled lab setting.

“It's not a new problem,” said Kristi Hamrick with Students for Life of America. “Research related to pregnant women and minors has always been complicated. It all comes down to: whose pregnancy are you going to risk for your curiosity?”

The average pregnant woman in the U.S. takes four prescription medications, and more than 90 percent take at least one. But for the vast majority of drugs approved by the FDA in recent decades, there is no data about their potential to cause birth defects.

For a long time, beginning in the late 1970s, pharmaceutical companies were barred from including any women of childbearing age in their Phase I and early Phase II drug trials — even women who used contraception, who were single, or whose husbands had undergone a vasectomy. That policy came after a rise in birth defects caused by a sedative drug, but the FDA acknowledged in the 1990s that it was too “rigid and paternalistic,” and moved to require better gender representation in clinical trials.

Still, the federal government kept the designation of pregnant women as a “vulnerable population” in research until 2018, lumping them in with children, prisoners, people with learning disabilities and other groups that can’t give informed consent.

But not only were many drugs on the market today tested before those policy changes, scientists and pharmaceutical companies still aren’t enrolling enough pregnant women — or enough women, generally — even though they’re now allowed to do so. Women remain significantly underrepresented in studies of everything from cancer to cardiovascular disease to blood disorders, which the Office of the Inspector General for HHS warned in 2024 puts them “at greater risk of having an adverse drug reaction.” As recently as 2018, for example, the FDA had to intervene to require a lower dose of the sleep aid Ambien for women — 25 years after the drug’s approval — after an increase in car accidents involving women drivers led researchers to discover that the pills’ effects linger longer in female bodies.

In this information vacuum, women’s health advocates fear Health Secretary Robert F. Kennedy Jr.’s focus on drugs used by pregnant women will deter them from taking needed medications, exacerbating mental and physical conditions that could put them and their fetuses at risk.

“The conditions people use acetaminophen to treat during pregnancy are far more dangerous than any theoretical risks and can create severe morbidity and mortality for the pregnant person and the fetus,” cautioned Steven Fleischman, the president of the American College of Obstetricians and Gynecologists. “Maternal fever, headaches as an early sign of preeclampsia, and pain are all managed with the therapeutic use of acetaminophen, making acetaminophen essential to the people who need it.”

The Trump administration cited a meta-analysis of prior studies published in August by a group of scholars led by the dean of Harvard’s public health school as evidence supporting its recommendation that pregnant women avoid Tylenol. Those researchers said they’d found a link between use of the drug during pregnancy and children born with neurodevelopmental disorders including autism — though not evidence of causation — and said pregnant women should be warned.

Yet Tylenol is just the administration’s latest target. At a recent meeting of HHS’ vaccine advisory panel, members selected by Kennedy announced a new working group that will review the safety of all vaccines currently recommended for expecting moms. The FDA has also cast doubt on the safety of antidepressants for pregnant women, and pledged a review of the safety of the abortion medication mifepristone. And, earlier this year, Kennedy bypassed an expert advisory panel and stopped recommending that pregnant women get vaccinated for Covid-19, citing a risk of miscarriage that researchers and doctors’ groups dispute.

Though that move was later quietly overruled by the CDC, the announcement underscored yet another data deficit. Pregnant women were excluded from early Covid vaccine trials, fueling doubt about their safety, allowing misinformation to fill the vacuum, and prompting many to avoid them. Though later studies confirmed the shots were safe and effective for both mothers and developing fetuses, the damage was already done. Many unvaccinated pregnant women became severely ill and died from Covid, and the vast majority of infants hospitalized for Covid between 2022 and 2024 were born to mothers who didn’t get the shot. Even today, uptake of the vaccine among pregnant women in the U.S. remains low — below 20 percent.

Clinicians fear a similar dynamic with Tylenol — the only over-the-counter drug recommended for pregnant women to manage pain and fevers. Because other over-the-counter painkillers, including Advil and generic ibuprofen, carry known risks of birth defects, the new guidance on Tylenol could leave many with no other option, leading to unchecked fevers and other health conditions proven to increase the risk of miscarriages and birth defects.

“The rhetoric being used, the fear that is being instilled in providers and pregnant people has really negative consequences,” Whelan said. “And once bad information gets out there and gets baked into people’s [online] algorithms, it makes it so much harder to reverse the damages of misinformation.”