Which vaccine is contraindicated in pregnancy?

Appeared in: BTSC Staff Nurse 31 July-2025

Explanation

The Measles, Mumps, and Rubella (MMR) vaccine contains live, attenuated (weakened) viruses.
Live virus vaccines are contraindicated during pregnancy due to the theoretical risk that the vaccine virus could cross the placenta and infect the fetus, potentially causing birth defects.
Although the teratogenicity of the MMR vaccine is theoretical and has not been confirmed, it is standard practice to avoid it during pregnancy as a precaution.
Women who are not immune to rubella should be vaccinated postpartum.

Option A: Tetanus toxoid is an inactivated toxoid, not a live virus. It is safe and recommended during pregnancy as part of the Tdap vaccine.
Option B: The Hepatitis B vaccine is a recombinant (inactivated) vaccine and is considered safe for administration during pregnancy, especially for women at risk of infection.
Option D: The inactivated influenza vaccine (flu shot) is not a live virus and is strongly recommended for all pregnant women during flu season to prevent severe illness in the mother and provide passive immunity to the newborn.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Vaccine contraindications in pregnancy as background academic context rather than a clinical decision trigger.
A core nursing responsibility is to screen for pregnancy before administering any live vaccine. Always ask female patients of childbearing age about the possibility of pregnancy.
Patient education is crucial. Nurses must explain the rationale for recommending certain vaccines (like Tdap and flu shot) and avoiding others (like MMR) during pregnancy.
What if? A woman receives an MMR vaccine and then discovers she is pregnant. The nurse should reassure her that while the vaccine is contraindicated, there is no evidence that it causes birth defects. The patient should be advised to inform her obstetrician, but termination of pregnancy is not recommended based on this exposure alone.

How to Approach the Question

First, identify the key terms in the question: 'vaccine' and 'contraindicated in pregnancy'.
Recall the fundamental principle of immunization during pregnancy: live attenuated vaccines are generally contraindicated, while inactivated vaccines and toxoids are generally safe.
Scan the options to determine the type of each vaccine.
Option A (Tetanus toxoid) is a toxoid (inactivated).
Option B (Hepatitis B) is an inactivated (recombinant) vaccine.
Option C (MMR) is explicitly labeled as a 'live virus' vaccine.

Concept Tested & Keywords

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E6 Pharmacology Nursing Lilley 11e Part 3 p. 152-154

E6 Obstetrics Williams p. 84-90

Practise the full BTSC Staff Nurse 31 July-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.