Pregnant mothers are told to always consult their gynaecologist or pharmacists if they are taking any medications or are thinking of starting some medications. These may include over-the-counter medications, dietary or herbal products. Data pertaining to pregnancy category of medications can be sketchy and debatable; pharmacists often make their recommendations based on quality of the available resources and risk-benefit ratio. With initiatives such as "Treating for Two1" by the Centres for Disease Control and Prevention (CDC), it is delightful to know that many organisations worldwide are committed to understanding more about medication use in pregnancy.

Understanding the magnitude of the problem - Pregnancy and medication use

Many pregnant women take at least one medication during pregnancy. The use of four or more medications during pregnancy has doubled over the last three decades. Many pregnant women have comorbidities such as epilepsy and asthma2. These existing medical conditions may change during the course of pregnancy. There is therefore an urgent need for pharmacists to be well informed on the safety profile of medications and give the best recommendations to their patients.

Revamping the drug and pregnancy category

The old US Food and Drug Administration (FDA) drug classification system, developed in the 1970s, classifies drugs using letter of the alphabet to denote risks, with X being the most dangerous and A being the safest. However, this system has been cited multiple times to be flawed, as many drugs fall into Category C, and most will suggest a lack of data use during pregnancy, which was not necessarily the case3. Pharmacists often have to dig through primary literature such as PubMed and then consolidate and weigh the risks detected in case reports. On top of that, the old system mentions little on risks of teratogenicity, which is in fact, is often the most crucial information required to determine risk-benefit ratio.

In 2014, FDA revamped this system and named the new system as the "Pregnancy and Lactation Labelling Rule” (the PLLR or final rule). The PLLR removes pregnancy letter categories – A, B, C, D and X. Current labelling will include contact information for pregnancy exposure registries. This new database collects and maintains data on the effects of medications used by pregnant women. Pregnant women are encouraged to enroll in these studies if they are taking drugs or biological products for which there is a registry. This new registry also will publish information on the risk to the reproductive potential of males and females2. This new system is likely to be more helpful for pharmacists to evaluate safety profile of medication use pre- and postpartum for a woman, as well as for their spouse.

What’s next?

Focus in the few years to come will likely include the the FDA making it mandatory for drug companies to publish data on pregnancy risk with the new PLLR system. Pharmaceutical companies are also advised to publish updated warnings of their medications using reports from post-marketing surveillance.

What are the reliable resources for now?

The change of classifying medications and their risks to pregnancy is a large undertaking that will take several years to complete. But in the meantime, there are still some good and reliable resources which pharmacists can use to determine the safety profile of medications:

1. Drugs in Pregnancy and Lactation4

This reference is a commonly cited reference for use in assessments of safety profiles for pregnancy and lactation. The book is published approximately every three years. However, the latest version of the book still adopts the old FDA A to X Pregnancy Categories.

2. Micromedex

This is a paid subscription portal which is easily accessible via the internet. Micromedex updates their information regularly. The portal also contains the TERIS and Shepard's Catalogue of teratogenic agents, which provides the magnitude of teratogenicity risk (from low to high risk), and quality and quantity of data (from fair to excellent) to which risk estimate is based. It includes both the US and Australian pregnancy risk classifications. MIMS

Read more:
Pharmacists: How to decide if a medication is safe for breastfeeding mothers
A pharmacists’ advice for common pregnancy symptoms
5 deadly drug interactions every pharmacist should know

1. Treating for Two. Centers for Disease Control and Prevention. Available at: Last accessed 10 October 2016.
2. Pregnant? Breastfeeding? Better drug information is coming. Food and Drug Administration (FDA), United States. Available at: Last accessed on 10 October 2016.
3. FDA revamps system explaining the risks of medications during pregnancy. New York Times, 3 December 2014. Available at: Last accessed on 10 October 2016.
4. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk Sixth Edition. Gerald G. Briggs BPharm FCCP (Author), Roger K. Freeman MD (Author), Sumner J. Yaffe MD (Author). Available at: Last accessed on 10 October 2016.