UWorld Maternity Practice Test Prep & Questions Study Guide

Live vaccines are contraindicated during pregnancy due to the potential risk of the vaccine causing disease in the developing fetus. These vaccines contain a weakened form of the virus or bacteria, which is generally safe for healthy individuals but poses a risk in pregnant women. The immune system is altered during pregnancy, which may lead to complications if a live attenuated virus were to become pathogenic.

In contrast, inactivated vaccines do not pose this risk as they contain killed pathogens, and subunit and recombinant vaccines generally comprise only specific parts of the pathogen, thus they also don’t compromise fetal development. Therefore, it is essential for pregnant women to avoid live vaccines to ensure the safety and health of both mother and baby.