The Safety of Acetaminophen Use During Pregnancy: A Review of Current Evidence

 The moment a woman finds out about a pregnancy, every decision becomes about the unborn baby as well as herself. How do expecting mothers make decisions to keep themselves and their child safe with conflicting information about the potential detriments? The simple answer is to turn to the research and accepted theories based on research and data. While knowing the direct relationship between an individual drug and outcome for a baby is nearly impossible to achieve for a multitude of reasons, researchers have been able to draw conclusions about the safety versus hazard of a multitude of drugs during pregnancy. When determining if any drug is “safe” to take during pregnancy, a drug's potential to cause birth defects is placed into different categories. According to the American Academy of Family Physicians, the FDA has placed drugs into 5 of these categories. In category A drugs, controlled studies did not demonstrate any risk to the fetus, and the possibility of harm is low. In Category B drugs, animal studies have not shown fetal risk, but there have not been human studies conducted OR animal studies have shown adverse effects in the first trimester but no risk in later trimesters. In category C drugs, animal studies have shown adverse fetal effects, or controlled animal/human studies are not available. Category C drugs should only be administered during pregnancy if the benefits outweigh the possible risk to the fetus. In category D drugs, there is evidence of fetal risk related to the use of the drug, but may be used in a life threatening situation where there is no better alternative. The final category is category X. In category X drugs, studies have demonstrated abnormalities and there is no possible benefit which would outweigh the risks. Acetaminophen specifically has been classified as a category B drug. To some, category B may be interpreted as it poses risk, but this is not entirely accurate. A drug can not be classified as category A unless human studies have been done and conclusive to indicate no harm in any trimester. This controlled study can not be conducted for ethical considerations. Category A drugs are limited to vitamins and supplements at this time. When any drug is taken during pregnancy, even those considered category A, women are advised to consult with their providers. Acetaminophen is used as a fever reducer and pain reliever. Its ability to reduce fevers in pregnancy, especially the first trimester, is its most important function. Duke Health has published new evidence that may suggest the long-known theory that fevers, especially in early pregnancy, are directly correlated to some birth defects is more accurate than we initially thought. According to Dr. Eric Benner, a neonatologist and assistant pediatrics professor at Duke, it was previously not known if the virus causing the fever or the fever itself was the source of the potential birth defects, but this new data is indicating that the cause of the fever is neglectable. The actual fever causes harm regardless of source. Also according to Dr. Benner, “The animal models suggest a portion of congenital birth defects in humans might be prevented if fevers are treated through means including the judicious use of acetaminophen during the first trimester.” In their studies, researchers found that neural crest cells, which are critical for the heart, face, and jaw, have temperature sensitive ion channels just like those in sensory cells. Researchers found that when crest cells with TRPV1 and TRPV4 ion channels were placed in fever-like conditions, the embryos subsequently had craniofacial deficits as well as heart defects such as double outlet right ventricle along with other outflow restrictions. In a world where we are so interconnected via the internet, it is more critical than ever for those in power to be distributing accurate information, but also for individuals to take it upon themselves to fact check the information that they receive regardless of the source. 

https://www.aafp.org/pubs/afp/issues/2003/0615/p2517/jcr:content/root/aafp-article-primary-content-container/aafp_article_main_par/aafp_tables_content.print.html 

https://corporate.dukehealth.org/news/how-fever-early-pregnancy-might-cause-heart-facial-birth-defects