Dishes like ceviche, where shrimp is marinated in citrus juice, often raise questions about safety during pregnancy. While seafood offers important nutrients for fetal development, the preparation method is a major concern for foodborne illness. Determining if lime-cured shrimp is safe requires reviewing how acid preparation differs from traditional heat cooking.
Acid Curing is Not Heat Cooking
The preparation method used in ceviche, known as acid curing, causes a chemical transformation in the shrimp’s protein. The acid from the lime juice, primarily citric acid, denatures the proteins, similar to applying heat. This denaturation changes the shrimp’s color from translucent gray to opaque pink or white and firms up its texture, giving the appearance of being cooked.
This chemical change does not achieve the sustained, high internal temperature necessary for true pasteurization. Heat cooking, or thermal denaturation, reliably kills harmful pathogens by disrupting their cellular structures. Acid curing does not generate enough energy to consistently eliminate bacteria, viruses, or parasites present in raw seafood.
Research has demonstrated that dangerous bacteria such as Listeria monocytogenes can survive the acid curing process. Studies show that a high percentage of viable L. monocytogenes cells remain even after exposure to the acidic environment of lime juice. Since a pregnant person’s immune system is naturally suppressed, the risks associated with this bacterial survival are significantly elevated.
General Seafood Safety and Mercury Levels
Concerns regarding seafood during pregnancy often center on mercury, a heavy metal that can negatively affect a developing nervous system. Shrimp is classified as a “best choice” seafood because it contains very low levels of mercury, making it safe and beneficial when prepared correctly. Health organizations suggest pregnant individuals consume 8 to 12 ounces of low-mercury fish, like shrimp, per week to ensure adequate intake of nutrients like omega-3 fatty acids.
Beyond mercury, raw or undercooked shrimp presents other contamination risks, including various bacteria and parasites. These can include Vibrio bacteria, which naturally inhabit certain coastal waters and can cause severe illness if ingested. Proper handling and cooking are the two most effective steps to mitigate the risk of cross-contamination and general foodborne illness.
Preparing Shrimp Safely During Pregnancy
The rule for consuming any type of seafood during pregnancy is that it must be cooked thoroughly using heat. To ensure safety, shrimp must reach an internal temperature of 145°F (63°C). This temperature threshold is sufficient to destroy common foodborne pathogens like Listeria and Vibrio. A food thermometer is the most reliable way to confirm this temperature has been met, but the shrimp should also appear entirely opaque with a pink or white color.
Safe preparation methods include boiling, grilling, sautéing, or baking the shrimp until they are firm throughout. Any dish that relies on acid curing, such as ceviche, or uses raw shrimp, should be avoided during pregnancy due to the risk of listeriosis. When a pregnant person contracts a foodborne illness, complications can be severe, potentially leading to miscarriage or stillbirth. Adhering to the 145°F standard provides protection for both the pregnant person and the fetus.