During pregnancy, many foods that are considered safe under ordinary circumstances become foods to avoid. This is because certain food items can cause damage to an unborn baby, either through risk of infection or birth defects. In general, you should stringently avoid raw and undercooked meats during pregnancy, and oysters are no exception.
To understand why the food you eat can affect your baby so significantly, it helps to understand how you and your baby are connected to one another. Though you don't share a blood supply, your blood vessels nevertheless lie right next to your baby's blood vessels at the interface of the placenta and the uterine lining. Nutrients and oxygen cross from your blood to your baby's, and waste from your baby passes to you. Many substances, including some bacteria, can also cross the placenta.
Like undercooked meats, raw oysters are often contaminated with bacteria. One particular species quite common in raw oysters is Vibrio vulnificus, notes SafeOysters.org. The Vibrio bacteria survive in salt water and thrive in shellfish like oysters and clams. Anyone consuming raw oysters is at risk of infection -- in fact, raw oysters are among the most common sources of seafood-borne food poisoning.
The Vibrio bacteria cause digestive symptoms if you ingest them. Typically, you get stomach pain, diarrhea and nausea, says SafeOysters.org. However, if you have a weak immune system, the infection is much more serious and can result in a skin infection and more significant gastrointestinal effects. Pregnant women are particularly at risk because their immune systems are suppressed relative to the immune systems of most adults.
The effects of Vibrio upon a developing fetus are not well-known. However, many other bacteria that cause food-borne infection can cross the placenta and damage or kill a developing baby. The American Pregnancy Association notes that you should completely avoid raw and undercooked oysters throughout your pregnancy.
While raw oysters are unequivocally forbidden during pregnancy, you can eat fully cooked oysters, write Heidi Murkoff and Sharon Mazel in their book "What To Expect When You're Expecting." Make sure that the oysters are truly cooked through and have a firm texture, and eat them right away -- stored seafood, even in the refrigerator, can start to go bad before it starts to smell.
- SafeOysters.org: Introduction to Vibrio Vulnificus
- American Pregnancy Association: Food to Avoid During Pregnancy
- “What to Expect When You’re Expecting”; Heidi Murkoff and Sharon Mazel; 2008
- Jupiterimages/Comstock/Getty Images
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.