Risks of Listeria to Your Baby

Quick answer: Listeria during pregnancy can cause miscarriage (especially first-trimester), stillbirth, preterm labor, neonatal sepsis, and neonatal meningitis. About 20% of pregnancies with confirmed listeriosis end in fetal or newborn death even with treatment. Early IV antibiotics dramatically improve the odds. Outcomes depend on how early the infection is caught.

First trimester: miscarriage

Listeria infection in the first trimester is most likely to cause miscarriage, often before the mother even realizes she was infected. A 2017 University of Wisconsin–Madison study showed that listeria could pose a serious miscarriage threat in early pregnancy at infection levels previously thought too low to cause harm.

The bacteria reach the placenta through the bloodstream, then invade and replicate in placental tissue. In some cases the maternal immune system eventually mounts a response — but that response itself can cause a miscarriage as the body tries to clear the infection. In other cases the bacterial load in the placenta directly disrupts the pregnancy.

Second and third trimesters: stillbirth and preterm labor

Later in pregnancy, listeriosis more commonly causes preterm labor and stillbirth. The bacteria cross the placenta and infect the amniotic fluid and the fetus directly. Symptoms in the mother are often still flu-like and easy to miss; the first sign that something is wrong may be reduced fetal movement or the onset of preterm contractions.

About 20% of all pregnancies with confirmed listeriosis end in fetal loss, according to the American Pregnancy Association. Of newborns who are born alive but infected, roughly 3% die in spite of antibiotic treatment.

Early-onset vs. late-onset neonatal listeriosis

Early-onset (within the first week of life)

These babies were infected in utero, before delivery. They are often born premature and often quite sick — with sepsis (a bloodstream infection), respiratory distress, pneumonia, low Apgar scores, and sometimes a characteristic rash called granulomatosis infantiseptica. Up to about one-third of early-onset cases die even with intensive NICU care.

Late-onset (about 1 to 6 weeks after birth)

These babies are usually born at term, looking healthy, and develop symptoms a few days to several weeks later. The infection is most often acquired during delivery — passing through a birth canal that has been colonized by the bacteria, or contact with the mother’s intestinal flora. Late-onset listeriosis typically presents as meningitis (inflammation of the membranes around the brain and spinal cord). Survival is better than early-onset, but survivors can have lasting neurological effects depending on how quickly meningitis was treated.

What treatment can change

The single biggest factor in the outcome is how quickly the mother starts IV antibiotics. ACOG’s committee opinion recommends that pregnant women with confirmed listeriosis — and in many cases pregnant women who have only been exposed to a recalled food and are symptomatic — be started on antibiotics promptly, often before culture results come back.

Treatment is covered in detail on the diagnosis and treatment page. The short version: high-dose IV ampicillin for two weeks, sometimes longer, sometimes paired with gentamicin in the most serious cases.

If a contaminated food caused your loss

Losing a pregnancy or a newborn to a preventable foodborne infection is devastating in a way that’s hard to put into words. The food was sold in violation of federal law. The companies that produced it have legal responsibility. The medical bills are real and ongoing. None of that makes the loss less, but pursuing a case can stop the practices that caused the contamination from happening to another family.

The food safety attorneys at Pritzker Hageman handle these cases nationally. Eric Hageman recently won $4.5 million for a baby born with listeriosis after a contaminated-food exposure, and the firm has recovered over $3 million for a mother who lost her unborn babies to listeriosis. Their full overview is at Pritzker Hageman — Can I Sue if My Baby is Born with Listeriosis? and Pritzker Hageman — Can I Sue for a Miscarriage Caused by Listeriosis?.

Sources: CDC — People at Increased Risk · Cleveland Clinic — Listeria & Pregnancy · ACOG — Management of Pregnant Women With Presumptive Exposure · American Pregnancy Association — Listeria in Pregnancy.