Name a vaccine that is contraindicated in pregnant women.

The MMR (measles, mumps, rubella) vaccine is contraindicated in pregnant women primarily because it is a live attenuated viral vaccine. During pregnancy, there is a higher risk of complications for both the mother and the fetus if a live vaccine is administered. Live vaccines can potentially cause harm to the developing fetus, including congenital defects or miscarriage.

In contrast, the Tdap, influenza, and pneumococcal vaccines are not contraindicated for pregnant women. The Tdap vaccine is recommended during each pregnancy to protect both the mother and the newborn from pertussis. The influenza vaccine is also advised for pregnant women to reduce the risk of flu complications during pregnancy. The pneumococcal vaccine is generally safe and may be recommended in certain cases for pregnant women who are at increased risk for pneumococcal disease.

Understanding the nature of the vaccines and the implications of administering live vs. inactivated vaccines during pregnancy is key to recognizing why the MMR is specifically contraindicated.