Medications in Pregnancy

Medications in Pregnancy

July 15, 2022

Dear Colleagues,

Welcome back to Pharmacy Phriday.  In past installments, references have been made to the pregnancy class of various drugs.  For each of the medications included in UH’s protocol, the pregnancy class is listed at the top of the medication information page. It serves as a quick reference when considering the administration of a medication to a pregnant or breastfeeding patient.  The pregnancy class descriptions (see below) are also listed in the protocols and hyperlinked in the pdf version for the provider’s quick access.

Administration of a medication to a pregnant female, a female who may be pregnant, or a mother breastfeeding her child should be done with extreme caution.  Pregnancy can affect the absorption, distribution, and elimination of medications and threaten the life of the patient and fetus or have harmful effects on the developing fetus.  In the case of a nursing mother, medications may be passed onto the child through breast milk.  Medication administration in the pregnant or nursing female should only be done when the potential benefits outweigh the risks.   However, as stated in Nancy Caroline’s Emergency Care in the Streets, “in situations where there is a direct threat to the life of the patient, it is often necessary to administer a higher risk medication to preserve the life of the mother, regardless of the risk to the unborn child.”

Of all the medications provided in our UH drug boxes, most are category C (should only be taken if the benefit justifies the fetal risk). A few medications (ASA, Valium, Versed, Doxycycline) are category D drugs (evidence of risk - studies in pregnant women have demonstrated a risk to the fetus; potential benefits of the drug may outweigh the risks). One medication, Amiodarone, is category X (contraindicated - studies in pregnant women have demonstrated a risk to the fetus, and/or human or animal studies have shown fetal abnormalities; risks of the drug outweigh the potential benefits) and generally should not be administered.  Lidocaine is an acceptable alternative in the case of Amiodarone. 

Interestingly, the pregnancy risk categories currently used in our UH protocol have been replaced.  In 1979, the FDA established the five letter risk categories - A, B, C, D, or X - to indicate the potential of a drug to cause birth defects if used during pregnancy. Over many years, the pregnancy risk categories were viewed as overly simplistic regarding pregnancy and lactation prompting the FDA to develop a newer system entitled the Pregnancy and Lactation Labeling Rule (PLLR). The new system became effective in 2015 and has been phased in over several years.  The system is designed to replace the simplistic category with more detailed information for the provider presented in a narrative form. According to some resources, the new rule has several potential limitations, and the transition to the newer system has been challenging.  Despite the FDA’s overhaul of the classification system, many physicians have continued to use the traditionally accepted pregnancy categories for medications that existed prior to the 2015 implementation of the PLLR. 

The use of medications in pregnancy and lactation presents a challenge to all health care providers and should include a risk-benefit assessment.  For these patients who are ill, the first consideration should always be one that does not involve a drug. Of course, there are many situations where there is no choice but to use a medication.  “In general, medications and interventions that protect the life and health of the mother are usually in the best interest of the dependent fetus” (Caroline’s Emergency Care in the Streets, 8th edition).  When feasible, the paramedic should consider medical direction as a resource to assist in making that risk-benefit analysis. 

Till next time, stay safe!


The UH EMS-I Team

University Hospitals