Monterey Jack cheese is generally safe to eat during pregnancy, provided it is made with pasteurized milk. Most commercially available Monterey Jack in the United States uses a heat treatment process, which eliminates harmful bacteria that could pose a risk to a pregnant woman and her developing baby. Careful selection and preparation are necessary to reduce the potential for foodborne illness.
The Critical Factor of Pasteurization
Pasteurization involves heating the milk to a specific temperature for a set duration, which effectively kills illness-causing bacteria like Listeria monocytogenes. Since most Monterey Jack is classified as a semi-hard cheese, it is typically produced using pasteurized milk, making it a safe choice for consumption. Checking the product label is the most important step in verifying safety, as it should clearly state “pasteurized” or “P.”.
If you are purchasing from an artisanal producer, farmer’s market, or a smaller dairy, you should always confirm the milk’s treatment status, as some specialty Monterey Jack may be made with raw milk. Raw milk cheeses carry a higher risk of bacterial contamination and should be avoided entirely during pregnancy. Even when the cheese is pasteurized, it is wise to buy pre-packaged blocks rather than pieces cut from a large wheel at a deli counter, as this reduces the potential for post-production cross-contamination.
Identifying Other High-Risk Cheeses
While pasteurized Monterey Jack is safe, other cheese varieties carry a higher risk and should be avoided unless cooked thoroughly. These high-risk cheeses generally fall into two categories: those made with unpasteurized milk and soft, mold-ripened varieties. Any cheese made from raw or unpasteurized milk, regardless of its texture, should be excluded from the diet. This includes certain artisanal cheddars, some Mexican-style cheeses, and other varieties where the milk has not undergone heat treatment.
The second category includes soft cheeses like Brie, Camembert, Feta, Blue cheeses, and soft Mexican cheeses such as Queso Fresco. These varieties pose a greater risk because their high moisture content and lower acidity provide an ideal environment for Listeria to grow, even if they were pasteurized initially. The bacteria can contaminate the cheese during the aging, packaging, or handling processes after pasteurization. These soft cheeses become safe if they are cooked until they are steaming hot throughout, as the heat destroys any potential bacteria.
Understanding the Danger of Listeria
The reason for exercising caution with certain foods during pregnancy is the risk posed by the bacteria Listeria monocytogenes, which causes an infection called listeriosis. While listeriosis is a relatively rare illness in the general population, pregnant women are significantly more susceptible to infection due to changes in the immune system.
Symptoms in the mother are often mild and flu-like, including fever, muscle aches, and sometimes gastrointestinal issues, which can make the infection difficult to recognize. However, the bacteria can cross the placenta, leading to serious consequences for the developing baby. Infection can result in severe outcomes such as miscarriage, stillbirth, premature delivery, or life-threatening illness in the newborn. Because of these severe fetal risks, avoiding foods known to be sources of Listeria, such as unpasteurized dairy and certain soft cheeses, is a necessary precaution.