At your first prenatal visit, your health care provider likely talked with you about all the foods you should avoid during pregnancy — sushi, raw meat, deli meat and unpasteurized cheese — to prevent exposure to listeria. That's because consuming this bacteria can sometimes make you sick, and that extremely unlikely possibility becomes more likely when you're expecting.

Fortunately, there are steps you can take to greatly reduce your risk. Here's how, along with what happens if you think you've been exposed to listeria during pregnancy.

What is listeriosis?

Listeriosis is an illness caused by eating foods contaminated with the listeria monocytogenes bacteria. Keep in mind that simply being exposed to listeria, however, doesn't mean you'll develop an infection. In fact, most women who are exposed to listeria will not develop a listeriosis infection. 

How common is listeriosis during pregnancy?

While the odds of being infected with listeriosis are still very, very low, it is significantly (10 times) higher during pregnancy — and the potential of its causing problems in pregnancy is higher.[1]

What are the risks of listeriosis during pregnancy?

Listeria, unlike many other germs, enters the bloodstream directly and therefore can get to the baby quickly through the placenta. (Other food contaminants generally stay in the digestive tract.)

And an untreated infection can put baby at increased risk of more serious complications, including miscarriage, preterm labor, stillbirth or meningitis in newborns.[2]

Listeriosis symptoms during pregnancy

Listeriosis can be hard to detect, partly because symptoms can develop up to two months after eating contaminated food and can vary from severe to mild. If you think you may have eaten food that contains listeria, watch for flu-like symptoms including:

  • Fever over 100.6 degrees Fahrenheit
  • Muscle pain
  • Backache
  • Headache
  • Gastrointestinal symptoms, including diarrhea

Note that you may have fever only, or you might not have any symptoms at all. So it's important to contact your doctor even if you think what you're experiencing might be caused by something else.

What to do if you think you've been exposed to listeria during pregnancy

Many moms-to-be worry about possible exposure to listeria, especially after big food recalls. In many cases, a watch-and-wait approach for symptoms is all that's necessary. Doctors will usually recommend testing if you have symptoms like a fever or gastrointestinal troubles. 

If you're experiencing symptoms and your doctor suspects a listeriosis infection, he or she may order some tests to check for the bacteria and monitor your baby's health. If you have been infected, you'll get a prescription for antibiotics.

What should you do to protect yourself from listeria exposure during pregnancy?

One of the best ways to prevent listeriosis is to avoid foods that are most likely to be contaminated. These include:[3]

  • Hot dogs, lunch meats or cold cuts that are cold or heated lower than 165 degrees F
  • Refrigerated pâté and meat spreads
  • Refrigerated, smoked seafood (like smoked salmon)
  • Unpasteurized milk and soft cheeses (like feta, queso blanco, Brie and blue-veined cheeses)
  • Unpasteurized juices (if you're not sure whether a juice has been pasteurized, don't drink it)
  • Unwashed, raw produce
  • Alfalfa and other sprouts

A few more tips to stay safe from listeria during pregnancy:

  • Always wash produce (including those organic blueberries from the farmer's market) thoroughly in running tap water, even if you're planning to peel or cook it. 
  • As a precaution, even ready-cooked meats should be heated to steaming before eating.
  • When eating out, watch for signs that the restaurant doesn't follow basic sanitation rules (and it should be pretty obvious): Perishable foods are kept at room temperature, the bathrooms are unclean, it's open season for flies, etc.

Unfortunately it's impossible to know for sure if the food you buy today will be recalled tomorrow — making it impossible to avoid listeria entirely.

That said, the risk of contracting the infection from day-to-day eating is extremely low, even if you are expecting. So try not to let worries about possible food contamination consume you.

Instead, spend your energy focusing on what you can do: Eat a balanced, healthy pregnancy diet to help support you and your growing baby.