Pregnant women are told to avoid deli meat because it can harbor Listeria monocytogenes, a bacterium that is 18 times more likely to cause serious illness in pregnant women than in the general population. While listeriosis is relatively rare (about 12 cases per 100,000 pregnancies), the consequences for a developing baby can be devastating, including miscarriage, stillbirth, and preterm birth.
What Makes Listeria Different From Other Foodborne Bacteria
Most foodborne bacteria stop multiplying once food hits refrigerator temperatures. Listeria does not. It can continue to grow at temperatures as low as 24°F, well below the typical fridge setting of 40°F. This means that even properly refrigerated deli meat can accumulate dangerous levels of the bacteria over time. Only heating to 165°F or freezing at 0°F or below will stop it.
This cold tolerance is what makes deli meat a particular concern. Sliced turkey, ham, roast beef, salami, and other cold cuts are designed to be eaten straight from the refrigerator, giving Listeria an opportunity that cooking-before-eating foods don’t. The bacteria can also contaminate meat after it’s been cooked at the processing plant, during slicing, packaging, or handling at the deli counter.
Why Pregnancy Increases the Risk So Dramatically
During pregnancy, your immune system shifts to avoid rejecting the developing fetus. This natural suppression leaves you more vulnerable to certain infections, and Listeria is one of the most dangerous. With an incidence rate of 12 per 100,000 pregnancies compared to 0.7 per 100,000 in the general population, the increased susceptibility is significant.
What makes listeriosis especially alarming in pregnancy is that your own symptoms may be mild. The most common signs are fever, cough, abdominal or pelvic pain, and muscle aches. These can easily be mistaken for a flu or a routine pregnancy discomfort. The incubation period ranges from 24 hours to 70 days, which makes it difficult to trace back to a specific meal.
How Listeria Reaches the Baby
Listeria has a specific biological trick that most bacteria lack: it can cross the placental barrier. The placenta is lined with a protective layer of cells that normally keeps infections away from the fetus. Listeria produces a surface protein that binds to a molecule called E-cadherin found on those placental cells, essentially picking the lock to get through. It uses the same mechanism to cross the intestinal wall after you eat contaminated food. Once past the placenta, the bacteria can infect the amniotic fluid, the fetus, or both.
Research published in the Proceedings of the National Academy of Sciences showed that when Listeria invades placental tissue in the lab, it produces damage that mirrors the lesions found in placentas of women who had listeriosis during pregnancy.
The Stakes for the Baby
The consequences depend heavily on timing. Infection during the first trimester carries an estimated 65% risk of miscarriage. In the second or third trimester, the risk of fetal death drops to about 26%, but other serious outcomes take its place.
In a large national cohort study, deliveries following a Listeria infection had a preterm birth rate of 61%, compared to about 8% in unaffected pregnancies. The stillbirth rate was 13.5%, compared to 0.7%. Among surviving newborns who were infected, the fatality rate can reach as high as 20%, and those who survive may face long-term neurological problems and physical disabilities.
Which Meats Are Included
The CDC’s guidance covers more than just the sliced turkey and ham you picture at a deli counter. The “riskier” category includes all unheated deli meat, cold cuts, hot dogs, and fermented or dry sausages. That means pepperoni, salami, prosciutto, and similar cured meats carry the same warning when eaten cold or at room temperature. The curing and fermentation processes reduce but do not eliminate the risk of Listeria contamination.
Canned and shelf-stable meat products are considered safe without reheating. The canning process uses high heat in a sealed environment, which kills Listeria. So canned chicken, shelf-stable meat spreads, and similar products are fine to eat directly.
How to Eat Deli Meat Safely During Pregnancy
You don’t have to give up deli meat entirely. The CDC’s recommendation is to heat it to an internal temperature of 165°F, or until it’s steaming hot, before eating. This kills Listeria reliably. A microwave works, though heating in a skillet or toaster oven tends to produce more even results. The key is that the meat needs to be genuinely hot all the way through, not just warm.
If you’re making a sandwich, heat the meat first and then assemble. A melted-cheese panini pressed until the filling is steaming counts. A cold sub from a sandwich shop does not, even if the bread was toasted, because the meat inside may not have reached a high enough temperature.
For storage, keep your refrigerator at 40°F or below and use opened deli meat within three to five days. Freezing at 0°F stops Listeria from multiplying entirely, so storing deli meat in the freezer until you’re ready to cook it is another practical option.