Why Doctors Say ‘There Isn’t Enough Data’ in Pregnancy — And What That Actually Means

By Avni Loya

Imagine visiting your doctor while you're pregnant with a chronic condition- anything from arthritis, pain from an infection, or preeclampsia. You ask if a medication is safe to take, but the answer is often:

“There isn't enough data.”

This answer might seem scary at first, but it doesn't mean what you think. The reality is, there isn't enough consistent data online on how different types of medications affect you and your baby, and even published studies report contradicting data.

Let's look into a common example: Aspirin. It's very helpful! It treats preeclampsia, which affects the arteries that direct blood to the placenta. Aspirin is also used to treat IUGR, used as a tocolytic, and prevents gestational HTN. When paired with a drug called prednisone, it even reduces pregnancy loss in women with lupus. As we can see, Aspirin is wildly useful as a medication during pregnancy! Unless, of course, it causes cardiac defects or lowers your child's IQ. A research paper titled “Congenital heart disease in relation to maternal use of Bendectin and other drugs in early pregnancy” conducted an interview-based study on the association between maternal aspirin intake and congenital heart disease. The study found that “aspirin use in early pregnancy was associated with about a twofold increase in the frequency of defects in septation of the truncus arteriosus”, meaning there is a correlation to cardiac defects (Zierler 1985). However, a different study by Dr. Werler, studying data from a large surveillance program of babies with cardiac defects found “aspirin use during the first trimester of pregnancy does not increase the risk of congenital heart defects in relation to that of other structural malformations” (Werler 1989). According to a study on the association between IQ and maternal

aspirin, “Maternal aspirin use during the first half of pregnancy was significantly related to IQ and attention decrements in the exposed children” (Streissguth et al. 1987). This study explored the effect of children up to four years old. A study working with the same population of four year olds published the following: “It is concluded that an adverse effect of aspirin exposure on IQ is unlikely” (Klebanoff et al. 1988). Both studies included that more studies must be conducted to explore the effects of acetaminophen during pregnancy: “it would be desirable to have these findings replicated in other studies. Further follow-up of the children at a later age is

planned“ (Streissguth et al. 1987). According to Dr Waggle, “As of 2019 authorities state there is not ENOUGH data to truly estimate fetal risk.” That's why Dr. Waggle is authoring a systematic review, we need more data and studies on the effects of medicine during pregnancy. These examples with aspirin show contradicting research, and there are many other examples of medicine with limited understanding in this application:

a. Morphine: This drug is used to treat pain from an infection or disease, but could

potentially cause maternal respiratory depression or even death.

b. Celecoxib: Treats rheumatoid arthritis & osteoarthritis, but potentially causes elevated liver enzymes, bleeding or thromboembolism for the mother.

c. Diclofenac: Treats chronic pain, dysmenorrhea, and arthritis, but potentially causes premature ductal arteriosus closure (which leads to pulmonary hypertension) or miscarriage.

Image source: Wikimedia Commons, CC BY-SA license

There are countless pregnancy medications that need more data and information so pregnant women can feel confident with their treatment. Our study hopes to contribute to furthering this knowledge.

While there is a limited number of studies on pregnancy medications, there are studies upon studies on medications during labor, which raises the question: Why are there so many studies on medications during delivery but not medications women take at home? There are three main reasons: convenience, time-period, and ethical concerns. During delivery, medications are administered by doctors and nurses, making controlled studies easier. Mothers and babies are monitored 24/7, and there are millions of records for data. Research during labor is simply more convenient. Secondly, time. Exposure for labor and delivery medication lasts a

few hours, compared to months of exposure to at-home pregnancy medications. It is more difficult to track, and labor research is lower-risk with fewer limiting factors. Lastly, ethical considerations. Pregnant women are often excluded from trials because researchers do not want to risk harming the fetus. As Dr. Waggle explains, “Ethically, we cannot expose humans to teratogens.” This means there are fewer controlled studies on these medications.

The novel “Invisible Women” by Caroline Criado Perez discusses these issues and the

paradox it creates for research. Doctors avoid testing pregnant women to protect them, but this means pregnant women must make decisions about their pregnancy with limited information, which defeats the purpose of protecting them in the first place. The non-fiction work also discusses the “Gender Data Gap”, highlighting that historically, studies use males as test subjects by default. Because of this, many drugs and effects are based on male bodies, not females.

Let's revisit the scenario I presented with you at the beginning of this article. You ask your doctor about a specific medication during pregnancy, but research points in different directions, and they respond, “There isn't enough data.” There's a difference between an absence of data and evidence of harm. Even though your doctor said there isn't enough data, this doesn't mean the medication is bad for you, nor does it mean it's good. It just means there isn't enough information, which is arguably worse. A systematic review is a type of research study that analyzes many existing studies on the same topic. This helps scientists decide what the overwhelming majority of studies report and what the general consensus on association is for different types of medication during pregnancy. As we've seen, different research suggests different conclusions, which makes it even more important to compile what the majority says. It's hard to trust one study, but when more studies support the same conclusion, the conclusion is more reliable. By writing a systematic review, we hope to help pregnant women make informed choices about the medications they're taking.

References

Criado-Perez, C. (2020). Invisible women exposing data bias in a world designed for men Caroline Criado Perez. Vintage.

Klebanoff, M. A., & Berendes, H. W. (1988). Aspirin exposure during the first 20 weeks of gestation and IQ at four years of age. Teratology, 37(3), 249–255.

https://doi.org/10.1002/tera.1420370310

Streissguth, A. P., Treder, R. P., Barr, H. M., Shepard, T. H., Bleyer, W. A., Sampson, P. D., &

Martin, D. C. (1987). Aspirin and acetaminophen use by pregnant women and

subsequent child IQ and attention decrements. Teratology, 35(2), 211–219.

https://doi.org/10.1002/tera.1420350207

Werler, M. M., Mitchell, A. A., & Shapiro, S. (1989). The relation of aspirin use during the first

trimester of pregnancy to congenital cardiac defects. The New England journal of

medicine, 321(24), 1639–1642. https://doi.org/10.1056/NEJM198912143212404

Zierler, S., & Rothman, K. J. (1985). Congenital heart disease in relation to maternal use of

Bendectin and other drugs in early pregnancy. The New England journal of medicine,

313(6), 347–352. https://doi.org/10.1056/NEJM198508083130603