Listeria in Pregnancy: Symptoms and Prevention
Listeria in pregnancy — symptoms, risks, and how to prevent listeria infection.
Listeria (listeriosis) is a bacterial infection caused by eating food contaminated with the bacterium Listeria monocytogenes. For most healthy people it causes only mild illness, but during pregnancy it can be far more serious — affecting you, your placenta, and your baby. The good news is that the risk is low, and simple food hygiene measures make it lower still.
What Is Listeria and Why Does It Matter in Pregnancy?
During pregnancy, your immune system naturally becomes less active to protect your baby. This means infections that a non-pregnant person might shake off easily can become more serious for you. Listeria is particularly concerning because it can cross the placenta and infect the baby directly, potentially causing miscarriage, premature birth, stillbirth, or serious illness in a newborn.
The bacteria can grow at fridge temperatures, which is what makes it different from many other food pathogens — refrigeration does not stop it multiplying. Thorough cooking and avoiding high-risk foods are your main defences.
Symptoms of Listeria in Pregnancy
Symptoms can appear anywhere from a few days to several weeks after eating contaminated food, which makes it tricky to trace. Signs to look out for include:
- A high temperature (fever) of 38°C or above
- Muscle aches and flu-like symptoms
- Nausea and vomiting
- Diarrhoea
- Headache and fatigue
The difficulty is that these symptoms are also common in normal pregnancy. If you develop a fever alongside other flu-like symptoms, particularly if you have recently eaten high-risk foods, contact your midwife or GP the same day. Do not wait. If you feel very unwell, call 111 or go to your nearest maternity assessment unit.
Listeria can also sometimes cause complications with no obvious symptoms in the mother, which is another reason why routine antenatal care is so important.
Foods to Avoid to Prevent Listeria
The NHS advises pregnant women to avoid the following foods because they carry a higher risk of listeria:
- Soft mould-ripened cheeses such as Brie, Camembert, and blue-veined cheeses (unless cooked until steaming hot all the way through)
- Unpasteurised milk and dairy products
- Pâté of any kind, including vegetable pâté
- Ready-to-eat cold-smoked or cured fish such as smoked salmon (fine if cooked)
- Pre-prepared salads and deli coleslaw that have been sitting open
- Deli meats and cold cooked meats unless you heat them until piping hot (e.g. ham reheated, not eaten cold from a packet)
- Raw or undercooked meat of any kind
Hard cheeses such as Cheddar, Parmesan, and Edam are safe, as is cream cheese and cottage cheese.
Practical Food Safety Tips
Good kitchen hygiene reduces your risk significantly:
- Wash hands thoroughly before and after handling food
- Keep your fridge below 5°C and your freezer at -18°C
- Store raw meat at the bottom of the fridge, away from ready-to-eat food
- Use food before its use-by date — do not rely on smell or appearance
- Reheat leftovers and ready meals until steaming hot throughout, only once
- Wash salad leaves, fruit, and vegetables even if the packet says "ready to wash"
When to Seek Help
If you develop fever, muscle aches, or digestive symptoms — especially after eating any of the foods listed above — contact your midwife or GP promptly. Listeria is treated with antibiotics, and early treatment significantly improves outcomes for both you and your baby. Do not self-medicate and do not wait to see if things improve on their own.
Frequently Asked Questions
How do I know if I have listeria and not just a pregnancy bug?
It can be difficult to tell, as symptoms overlap with common pregnancy complaints and mild viral illness. The key warning sign is a fever of 38°C or above alongside flu-like muscle aches, particularly if you have recently eaten high-risk foods. In that case, contact your midwife or GP the same day rather than waiting. A blood test can confirm listeria infection if your healthcare team suspects it.
Is listeria common in the UK?
Listeria infection is rare in the UK. Pregnant women are at higher risk than the general population, but the overall number of cases reported each year remains small. The NHS and Food Standards Agency (FSA) carry out regular food safety monitoring, and UK food producers are required to follow strict hygiene standards. Following the food safety guidance above keeps your personal risk very low.
Can I eat out safely when pregnant?
Yes, with some care. In restaurants, avoid dishes containing the high-risk foods listed above unless they are cooked through (for example, a Brie en croûte baked until fully melted is safer than cold Brie on a cheeseboard). Ask staff about preparation if you are unsure. Pre-packed sandwiches from reputable retailers generally carry low risk because their supply chains are heavily regulated, but check the ingredients and use-by date. Your midwife can give you further guidance if you have specific questions.
Always speak to your midwife or GP if you have concerns about food safety during your pregnancy.
This article is for informational purposes only and does not constitute medical advice.
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