Which of the following is a contraindication specifically related to pregnancy?

Radiation exposure from CT and x-ray is considered a specific contraindication related to pregnancy because these imaging techniques involve ionizing radiation, which can pose risks to a developing fetus. During pregnancy, particularly in the first trimester, the fetus is more susceptible to the harmful effects of radiation, which can potentially lead to developmental abnormalities or increase the risk of childhood cancer. For this reason, alternative imaging methods that do not use ionizing radiation, such as ultrasound or MRI, are generally preferred for pregnant patients.

In contrast, while there are certain precautions when using contrast in MRI and some considerations for MRI itself, they are not characterized as absolute contraindications in pregnancy. Blood tests for infections are routinely performed and are safe during pregnancy, as these do not involve any exposure to radiation or other harmful agents. Thus, the option highlighting the risks associated with radiation exposure stands out as particularly relevant to the context of pregnancy.