Is Acetaminophen Safe While Pregnant?
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You may know that some medications aren't safe to take while pregnant, but you've probably received the green light from your doctor to take Tylenol. However, a recent study—published in the journal Nature Reviews Endocrinology—showed that there could be consequences from taking the drug acetaminophen (the active ingredient in Tylenol) during pregnancy.
"Prenatal exposure to APAP might alter fetal development, which could increase the risks of some neurodevelopmental, reproductive and urogenital disorders," a statement read. "[Pregnant people should] minimize exposure by using the lowest effective dose for the shortest possible time."
This is not the first time scientists have suggested acetaminophen may be dangerous during pregnancy, or—at the very least—place the fetus at risk. A 2016 study published in the journal Scientific Reports garnered similar results, although the test was done in rats, and another study, published in the International Journal of Epidemiology, found that children of individuals who took acetaminophen while pregnant had a higher risk of asthma.
What Are the Risks of Taking Acetaminophen While Pregnant?
Asthma aside, there are several risks to taking acetaminophen, or Tylenol, while pregnant. According to the authors of the most recent review—which is based on the recommendations of 29 studies—acetaminophen can alter fetal development, which in some cases could result in neurological, urological, and/or reproductive disorders in the infant.
"APAP exposure during pregnancy might increase risk of male urogenital and reproductive tract abnormalities, as studies have found an elevated risk of undescended testicles (cryptorchidism) and reduced distance between the anus and the base of the penis, a measure known as the anogenital distance (AGD)," the statement reads. "Prenatal APAP exposure has also been associated with earlier female pubertal development."
Behavioral conditions, such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, language delay (in girls) and decreased intelligence quotient, may also occur. What's more, the Scientific America study linked acetaminophen to reproductive issues, at least in rats. Rodents who were given the drug had female babies with fewer eggs, smaller ovaries, and smaller litters themselves as adults. Male babies had a smaller number of cells that led to sperm later in life, but they bounced back to normal by adulthood.
"It's important to remember that this study was conducted in rats not humans; however, there are many similarities between the two reproductive systems," says Richard Sharpe, Ph.D., who co-led the SA study at the University of Edinburgh's MRC Centre for Reproductive Health in the U.K. "We now need to understand how these drugs affect a baby's reproductive development in the womb so that we can further understand their full effect."
Tylenol During Pregnancy and Asthma Risk
Another study that actually did involve humans showed that the children of parents who had taken acetaminophen in pregnancy were more likely to have asthma at three and seven years old. Researchers in Europe looked at data from 114,500 children in Norway to compare those who had asthma (5.7 percent at three years old and 5.1 percent at seven) with those whose parents had taken acetaminophen during pregnancy, and found a link.
Even more important, the researchers were able to see why the meds were taken—for fever, pain, or the flu—and were then able to compare said data to parents who had the same symptoms but didn't take the drug. By looking at the data this way, they were able to rule out the symptom itself as being a reason for the increase in asthma risk. In addition, they looked at each parents' acetaminophen use outside pregnancy, to confirm that it was the drugs' use during pregnancy specifically, and not any outside factors or health behaviors, that was the cause. The study authors theorize that the drug could cause an increase in "oxidative stress" (the difficulty of the body to fight off toxins) during pregnancy, which is thought to raise the risk of asthma.
Although there have been other studies that looked at acetaminophen use during pregnancy and asthma, this was the largest, and was the first to compare a pregnant persons' symptoms with and without the drug to the risk of childhood asthma. But, the study authors weren't able to confirm the severity of the symptoms, or how much acetaminophen the pregnant person took.
Should You Take Advil or Tylenol While Pregnant?
Advil is already not recommended in pregnancy, especially during the last trimester, because of the risk of certain birth defects and complications for delivery. Tylenol is generally considered "safe" in pregnancy—although the FDA did recently review its position based on other studies concerning acetaminophen's safety, and found the research "too limited" to make any recommendations against its use.
That said, the benefits of taking any drug during pregnancy have to be weighed against the risks, i.e. being feverish or in a lot of pain during pregnancy isn't good either. However, all three studies suggest pregnant people should avoid taking acetaminophen unless it is medically necessary. "Pregnant women [people] should be cautioned at the beginning of pregnancy to: forego APAP unless its use is medically indicated; consult with a physician or pharmacist if they are uncertain whether use is indicated and before using on a long-term basis; and minimize exposure by using the lowest effective dose for the shortest possible time," a statement put forth in the Nature Reviews Endocrinology reads.
