Rachel Feltman: For Scientific American's Science fast I'm Rachel Feltman.
The President of the United States recently said that use of acetaminophen, commonly known under the brand name Tylenol, during pregnancy and early childhood may be linked to autism in children. But these claims are not backed by scientific evidence and highlight a much larger problem: we know shockingly little about the safety of medications during pregnancy.
For decades, pregnant women were excluded from most clinical trials, leaving doctors and patients to make decisions based on incomplete information. According to a recent study, 80 to 90 percent of people take prescription medications during pregnancy, but less than 1 percent of clinical trials include them. The result is a health care system that protects pregnant women. from research, not through it.
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Why we're missing this important data and what needs to change, explains Tanya Lewis, senior health editor at Scientific American.
Tanya, thank you very much for coming to talk to us.
Ask Lewis: Yes, thank you very much for having me.
Feltman: So, pregnancy and medications have been in the news a lot lately, you know, primarily because of the supposed link between acetaminophen and autism in children. Before we get into all the things you've unpacked in your recent partcould you give us a quick overview of these titles?
Lewis: So yes, you may have heard that Donald Trump and his Secretary of Health recently held a press conference where they announced that acetaminophen may be linked to autism in the child of a pregnant woman who takes the drug.
There is currently no high-quality evidence to support this association. It is based on correlations in studies that are poorly done and do not take into account the fact that, for example, Tylenol is often prescribed to treat infections that are themselves linked to autism in some studies.
So, you know, there were a lot of confounding factors and variables that weren't really mentioned at the press conference. And Tylenol is a drug that has been widely prescribed to children and pregnant people for decades and is known from clinical data and research to be generally safe at prescribed doses.
So this is obviously another case where I think the administration is going beyond the evidence and making a claim that is not actually supported by the data.
Feltman: Yes, and I think this has particularly resonated with people because the advice around medications and pregnancy is already so fraught and so confusing and so restrictive.
I think the President said something about pregnant people needing to “tough it out” instead of taking Tylenol. And given that Tylenol is a safe option for relieving pain and fever during pregnancy, unlike ibuprofen, which is known to have real risks, this has sparked a lot of conversation about what's missing from our factual, evidence-based drug recommendations during pregnancy, which you delved into in a recent article.
Could you start by just telling us where we are in terms of how much research has been done on medications during pregnancy?
Lewis: Yes, absolutely. I mean, you're pushing the button right, given the fact that while Tylenol itself is pretty well studied in pregnancy and is widely recommended because it's kind of the only, quote, unquote, “safe” pain management option that, you know, isn't associated with known fetal defects or anything like that, while that's true, the reality is that there just aren't a ton of studies in pregnant women people and drugs because, by definition, many pregnant people have been excluded from drug studies.
There are some historical reasons for this. It actually dates back to the days of thalidomide, a drug that was prescribed to treat morning sickness in Europe in the 1950s and 60s. And as we know, this drug was later found to cause terrible birth defects. And it really, you know, rightfully got people thinking about the potential negative effects of medications during pregnancy.
But as a result of all this experience, Congress decided to require more controlled drug studies, and that was a good thing; I mean, they didn't always do that with all the drugs, so that was good. The only downside was that they chose to classify pregnant people as “vulnerable” people and therefore unable to give informed consent to this type of research. This meant that in practice they were completely excluded, and we know nothing (or very little) about many drugs in pregnancy because they simply have not been studied in pregnancy.
Feltman: So what studies can researchers use to study medications during pregnancy, and what are their limitations?
Lewis: Right, I mean, this is something that we can and should study. I've talked to a lot of researchers and OB/GYNs who have said that, you know, there are ways to safely study medications in pregnant women. For example, we often conduct what we call observational studies, in which we follow pregnant women who are already taking medications to treat a chronic disease such as diabetes, heart disease, or even an infection such as HIV. And these are drugs that they cannot stop taking; these are, you know, life-saving drugs. And we can study the effect, if any, on the fetus by observing these people.
But we can also do studies where we look at maybe people who had two different babies and took the drug during one pregnancy but not the other, for example if it's a drug like Tylenol. There are these studies and you can compare them, and you – everything else between these people is pretty much the same, except that one was exposed to the drug and the other was not. So this is one way to do it.
And then, of course, you know, with clinical trials, these are the studies that are done before a drug is approved, and some of those safety studies that are done, you know, even before it becomes a clinical trial in humans. So we study these drugs in animals; we study them only for the sake of safety among a small group of people. And these studies can be done in non-pregnant people, and we can prove that a drug can be safe before we actually give it to a pregnant woman, and then we can look for any side effects in that population.
So there are definitely ways to explore this. There have been studies – just to put some numbers, you know, less than 1 percent of clinical trials now include pregnant women. So this is a huge gap in our knowledge and as some of the researchers who spoke to me said, you know, we protect people who are pregnant. from research instead through research.
And so we need to change this, because it is very important to take care of both the health of the mother and the fetus. If you do not treat a disease that is truly dangerous or harmful to the health of the mother, then the child will also suffer. So, you know, the whole couple needs to be treated.
Feltman: Yeah, one thing that really stood out to me in your article was the estimates of how things would go if we had some kind of randomized clinical trials of drugs that were found to be harmful to the fetus. Because, you know, I think it's understandable that there's a specter of fetuses that might be harmed in a clinical trial so that we can get this data, but people have thought about it and compared it to the actual harm done. Could you tell us a little more about this?
Lewis: Yes, completely. I mean, for example, if you think about thalidomide, that drug has caused birth defects in 10,000 or more children. So if a clinical trial of thalidomide were done on, say, 200 people, 33 of those children would have serious birth defects, but it would prevent 8,000 birth defects in other children because we would know about it, and then therefore those pregnant people would not take the drug during pregnancy. So we're talking about studying these drugs in a small and controlled group of people who knowingly agreed knowing what the potential risks might be. And we hope it will save many, many people and children from potential harm.
So, you know, it's never easy to think about any harm to the fetus or to the pregnant woman. But by not studying these drugs in these people, we are effectively going blind and not giving pregnant people the evidence that they need to make informed, safe choices during pregnancy. And the reality is that [as many as] Between 80 and 90 percent of pregnant women take prescription medications during pregnancy. So it's not that they don't take these medications – they just take them without evidence, just on the advice of doctors. And this is no one's fault. The reality is simply that there isn't enough data to really give people super-informed choices about most of these medications.
I have to say that there are some medications that are well studied and known to be safe. One example of medications that have been studied fairly well in pregnant women are SSRIs, which are antidepressants. And many pregnant women with depression or other mental health problems need these drugs to function. This is not an optional choice here. We know that poor mental health is one of the leading causes of postpartum mortality, so it is a huge problem in the US and other countries; we need to treat people who have these mental health problems. But this is always a conversation that people should have with their doctors, and if we can provide them with strong evidence and research to back up these decisions, then everyone will be safer.
Feltman: Thank you so much for coming to talk to us about this.
Lewis: Yes, thank you very much for having me. It was very nice.
Feltman: That's all for today's episode. We'll be back on Monday with our weekly roundup of science news.
Science fast I am producing, Rachel Feltman, along with Fonda Mwangi and Jeff DelViccio. This episode was edited by Alex Sugiura. Shayna Posses and Aaron Shattuck check the facts on our show. Our theme song was composed by Dominic Smith. Subscribe to Scientific American for more relevant and in-depth science news.
For Scientific American This is Rachel Feltman. Have a great weekend!
