Pregnant women require a diet with essential nutrients for the health of the mother and her baby. During pregnancy women and the fetus are especially more susceptible to three types of foodborne agents: Listeria monocytogenes (causing listeriosis), methylmercury, and Toxoplasma gondii (causing toxoplasmosis).
Listeriosis
Listeriosis is a disease caused by Listeria monocytogenes, a bacterium commonly found in the environment, which can then contaminate foods. Listeria monocytogenes can be transmitted to an unborn baby even if there are no illness symptoms for the mothers. In the first trimester, listeriosis may cause miscarriage. If contracted later in the pregnancy the disease may result in premature labor, low-weight infants, or stillbirth. Listeriosis is most commonly contracted during the third trimester when the mother's immune system is weakened.
Listeria can grow well at refrigerated temperatures while most other bacteria do not. Specific foods that you must AVOID to prevent listeriosis:
- Unpasteurized (raw) milk and dairy products or any food made with unpasteurized milk
- Soft cheeses such as feta, Brie, Camembert, blue-veined cheeses, or some "Mexican" cheeses such as "queso fresco" or "queso blanco," made with unpasteurized milk
It is okay to eat soft cheeses if they are made with pasteurized milk. Read the label carefully!
- Ready-to-eat meat products such as hot dogs, luncheon meat, bologna, or other types of deli meats
It is okay to eat these types of meats if they are reheated until steaming hot.
- Refrigerated pâtés and meat spreads
- Smoked seafood, often found at the deli counter or in the refrigerator section at the grocery store. Examples include: smoked salmon, trout, whitefish, cod, tuna, or mackerel (all commonly labeled as "nova-style," "lox," "kippered," "smoked", or "jerky"). These still need to be heated or cooked to bring them to safe temperature levels
You can eat canned or shelf-stable pâtés, meat spreads, salmon, tuna, and smoked seafood. Remember to refrigerate them after opening.
- Refrigerated ready-to-eat foods such as salads that are not cooked before eating
Methylmercury
Mercury is both a naturally occurring element in the environment and a byproduct of industrial pollution. When mercury is released into the air through pollution, it falls into bodies of water where it is transformed into methylmercury—the most toxic form of mercury. Over time, methylmercury is accumulated in the marine food chain. Larger fish that have lived longer and are consumers of the smaller fish are reported to have high levels of methylmercury.
Because methylmercury can harm the nervous system of an unborn child, pregnant women are advised not to eat these specific fish, which can have high levels of methylmercury: shark, swordfish, king mackerel, and tilefish.
Check local advisories for safe consumption of fish caught in your local areas. A good resource is the Environmental Protection Agency's site at http://water.epa.gov/scitech/swguidance/fishshellfish/fishadvisories/states.cfm.
Eating cooked fish/seafood gives you health benefits during pregnancy by providing omega-3 fatty acids. Pregnant women may eat up to 12 ounces per week of low mercury fish and seafood. Low-mercury choices include: shrimp, salmon, pollock, catfish, and canned light tuna. "Light tuna" is a good choice, as it is lower mercury than "white" tuna (albacore). Do not eat more than 6 ounces per week of albacore "white tuna."
Toxoplasmosis
Toxoplasmosis is an illness caused by Toxoplasma gondii (T. gondii), a parasite found in a number of things, including uncooked or raw meats, unwashed produce, soil, and places where cat feces may be found. T. gondii can be deadly to an unborn baby once the central nervous system has been developed. Babies infected with T. gondii can suffer defects such as hearing loss, mental retardation, even blindness; and in some children, T. gondii may cause eye and brain problems years after birth.
To prevent toxoplasmosis:
- Do not eat raw or undercooked meat, especially pork, lamb, and venison.
- Do not eat unwashed fruit and vegetables.
- Do not drink untreated water from rivers or pounds or in less-developed countries that may contain T. gondii.
- Do not use kitchen utensils that have had contact with raw meat.
- Do not handle cat feces, including dirty cat litter. Cats that eat raw meat and small animals are often hosts of T. gondii and this parasite can be found on a cat's feces. So, touching your mouth after handling anything that has coming into contact with cat feces can cause toxoplasmosis (e.g. cleaning a cat litter box).
References
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition. (n.d.). Food safety for moms-to-be. Available at https://www.fda.gov/food/people-risk-foodborne-illness/food-safety-moms-be
U.S. Food and Drug Administration. December 2022. Advice about Eating Fish. Available at https://www.fda.gov/food/consumers/advice-about-eating-fish
U.S. Department of Agriculture. 2022. Food Safety for Children and Pregnant and Breastfeeding Women. Available at https://wicworks.fns.usda.gov/resources/food-safety-children-and-pregnant-and-breastfeeding-women
Centers for Disease Control and Prevention. Food Safety for Pregnancy & Breastfeeding Food Safety: Keep yourself and your baby safe from toxoplasmosis. Available at https://www.cdc.gov/parasites/toxoplasmosis/gen_info/pregnant.html
U.S. Food and Drug Administration/EPA. February 2022. Questions & Answers from the FDA/EPA Advice about eating fish… Available at https://www.fda.gov/food/consumers/questions-answers-fdaepa-advice-about-eating-fish-those-who-might-become-or-are-pregnant-or