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Pregnancy is a delicate state both for mother and baby. An expectant mother is always conscious of what she eats, drinks, or applies on her skin. Yet often there is no way around taking medications during pregnancy, whether for a chronic illness or a passing flu. And then the worrying starts. What can I take safely? What must I completely avoid?
Pregnancy Categories were introduced by the FDA in 1979 in response to the “thalidomide tragedy”. Thalidomide (known as Distaval back then) was used in the 1950s to treat morning sickness and insomnia in pregnant ladies, and ended up causing birth defects in more than 10,000 newborns worldwide. The babies suffered severe organ and limb deformities (phocomelia), and around 40% of them died before age 1. Back then, there were no rules regulating the safety of drugs in pregnancy.
The Pregnancy Category system divides medicines into five categories, based on the studies available on them, whether on humans or animals, concerning their safety on a fetus.
Definitions and management strategies from the US Food and Drug Administration categories for drugs taken during pregnancy:
|A||Adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in the first trimester of pregnancy.||Because studies are not able to rule out the possibility of harm, (name of drug) should be used during pregnancy only if clearly indicated.|
|B||Animal reproduction studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies of pregnant women. Or animal studies demonstrate a risk, and adequate and well-controlled studies in pregnant women have not been done during the first trimester.||Because the studies of humans cannot rule out the possibility of harm, (name of drug) should be used during pregnancy only if clearly needed.|
|C||Animal reproduction studies have shown an adverse effect on the fetus, but there are no adequate and well-controlled studies of humans. The benefits from the use of the drug in pregnant women might be acceptable despite its potential risks. Oranimal studies have not been conducted and there are no adequate and well-controlled studies of humans.||(Name of drug) should be given to pregnant women only if clearly needed.|
|D||There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies of humans, but the potential benefits from the use of the drug in pregnant women might be acceptable despite its potential risks.||If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.|
|X||Studies in animals or humans have demonstrated fetal abnormalities or there is positive evidence of fetal risk based on adverse reaction reports from investigational or marketing experience, or both. The risk involved in the use of the drug in pregnant women clearly outweighs any possible benefits.||(Name of drug) is contraindicated in women who are or might become pregnant. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.|
(Source: study mentioned in Sources)
This system is helpful, but has many shortcomings:
- The system is a guide for physicians BEFORE an expectant mother starts her medication. It does not give guidance as to how to manage the pregnancy if the medication was already taken.
- The system does not take into account chronic illnesses that require long term treatment, like diabetes and epilepsy, and leaves it up to the physician to weigh the risks vs. the benefits.
- The system does not include information for nursing mother (on whether the medicine can pass through breast milk or not). This piece of information has to be cleared up separately on labels.
- There is a misconception that all medicines in the same category cause the same birth defect, which is not the case.
- There is another misconception that the categories represent increasing severity. B is more severe than A and C is more severe than B.
- The categories do not always distinguish between risks based on human vs. animal data.
The FDA acknowledged these shortcomings, and in 2008 started looking at developing a new, more efficient system for categorizing medicines for pregnancy and lactation.
Are You Interested in Helping?
Currently, many pharmaceutical companies are working on pregnancy registry studies to track the risks of various medicines on pregnancy and lactation. The FDA does not run the registries, but does have a list of them online. Basically, you check to see if the medicine you are required to take while pregnant has a registry, and if it does, you register, and the manufacturing company in charge will follow you and your growing child for a few years.
The aim is to keep track of any side effects you or your child might experience, and then compare these to non pregnant women taking the same medication. This will help identify any risks associated with the medicine you take, which will then lead to more educated decisions on what medicines to use while pregnant or lactating.
You can check out the Pregnancy Registries from here: http://www.fda.gov/ScienceResearch/SpecialTopics/WomensHealthResearch/ucm252397.htm
This is still a work in progress. Currently the FDA is working on the “Pregnancy and Lactation Labeling Rule”, which will eliminate the A,B,C,D,X pregnancy category system. In the meantime, the pregnancy category system is still being used.
As this is a site dedicated to skin care, here are a few examples of topical medicines and the pregnancy category assigned to them by the FDA:
- Pregnancy Category B: Azelaic acid, Clindamycin, EMLA, Metronidazole, Permethrin, Terbinafine.
- Pregnancy Category C: Adapalene, Benzoyl peroxide, Hydroquinone, Ketoconazole, Minoxidil, Steroids, Tretinoin, VANIQA (link to vaniqa post).
- Pregnancy Category X: Fluorouracil, Tazarotene.
Of course, this is not an exhaustive list. Always check with your doctor before starting any medication while pregnant or if planning on getting pregnant.
Thanks for reading! Remember, stop by my blog (elbashra.com) or tell your friends if interested in reading about skin care in Arabic!
- R. Law et al. FDA Pregnancy Risk Categories and the CPS: Do They Help or are they a Hindrance? Canadian Family Physician Journal 2010; 56 (3): 239-41.
- B. Barankin, A. Freiman. Dermnotes: Dermatology Clinical Pocket Guide. F.A Davis Company 2006.