The consequences of foodborne illness can be particularly devastating during pregnancy because both the woman and her fetus are at risk. Escalated production of progesterone during pregnancy leads to down-regulation of cellular (cell-mediated) immune functions. Many foodborne pathogens (and other pathogens) are intracellular pathogens, and infections caused by these pathogens are controlled by cell-mediated immunity. The pregnancy-induced decrease in cell-mediated immune functions leads to increased susceptibility of the pregnant woman to certain infections. Hepatitis E virus, Coxiella burnetii, Listeria monocytogenes, and Toxoplasma gondii are intracellular pathogens that have a predilection for the maternal-fetal unit and may induce serious disease in the mother and/or fetus. In the United States, T. gondii and L. monocytogenes are the most important foodborne pathogens in pregnancy, and these organisms can induce death or grave disease in the fetus and newborn. The pregnant woman, in order to protect herself and her fetus from the consequences of foodborne illness, must practice a high standard of food hygiene and personal cleanliness.