Listeria during pregnancy

By trimester

Weeks 1–13

1st trimester

First-trimester infection is most associated with pregnancy loss. The long incubation is what makes this stage confusing, since a meal from two weeks ago can be the source of today's fever.

Weeks 14–27

2nd trimester

The food rules are the same all the way through, and this is usually when appetite returns and the deli counter starts looking appealing again. Reheating cold cuts until steaming is the workaround most people land on.

Weeks 28–birth

3rd trimester

Infection later is linked to preterm delivery and to illness in the newborn, including late-onset listeriosis appearing one to two weeks after birth. Fever this late always deserves a call regardless of suspected cause.

What does the evidence show for listeria?

• Listeriosis comes from food carrying Listeria monocytogenes, most often unpasteurized milk and raw milk products, uncooked meat and fish, uncooked vegetables, deli meat, and soft cheeses. 1
• Symptoms can begin days to weeks after eating contaminated food and include diarrhea, fever, muscle and joint pain, headache, stiff neck, backache, chills, sensitivity to bright light, and sore throat. 1
• Pregnancies affected by Listeria have an increased chance of infection in the uterus, preterm delivery, and low birth weight, and severe infection increases the chance of stillbirth, while late-onset newborn listeriosis appears 1 to 2 weeks after birth. 1
• Pregnancy is a major risk factor, with incidence estimated at 10 to 100 times higher than in the general population, and maternal infection most often shows up only as flu-like symptoms and fever, or may be subtle or absent entirely. 2
• The bacterium survives low temperatures, high salt, and low pH and forms biofilms, which is why refrigeration alone does not stop it from persisting in ready-to-eat foods like cold deli meats, soft cheeses, and smoked seafood. 2

When should I call my provider about listeria?

Fever with flu-like symptoms such as muscle aches, chills, or headache after eating a recalled or high-risk food is the combination that needs same-day contact with your provider, even when it feels mild, since maternal infection can be subtle while it still affects the pregnancy. A stiff neck, confusion, or sensitivity to light alongside fever points toward a more severe infection reaching the central nervous system and needs prompt evaluation. Because symptoms can start days to weeks after the meal, mention a known recall or high-risk food to your provider even without symptoms, and always report contractions or reduced fetal movement. If you are ever unsure which side of the line you are on, make the call. Obstetric teams handle these check-ins as routine, not as overreacting.