Can I eat prawns while pregnant?

The verdict

A prawn that has just been cooked and is still hot is safe under every guideline on this page. A prawn that was cooked days ago, chilled, and is being eaten cold is the one that gets restricted, and the four countries handle it differently.

The NHS lists cooked shellfish, including prawns, crab, lobster, squid, mussels, scallops, clams and cockles, as safe to eat. It then separately names cold, pre-cooked ready-to-eat prawns among the foods to be careful with, with the instruction that these must be cooked until steaming hot.

Food Standards Australia New Zealand puts chilled, ready-to-eat seafood including cooked ready-to-eat prawns in its higher-risk table, with freshly cooked or thoroughly reheated to steaming hot as the safer alternative.

Ireland's HSE goes furthest, listing clams, oysters, scallops, prawns and mussels among foods to avoid in pregnancy, and adding that the risk is highest if they are pre-cooked.

The FDA approaches it from the other end: shrimp is on its Best Choices list for low mercury, and its instruction is to cook shrimp until it reaches an opaque, milky white colour, while avoiding raw or undercooked shellfish.

Two different hazards, and which applies when

Prawns carry two separate concerns and they do not overlap.

Raw prawns are a food poisoning risk in the ordinary sense: vibrio, salmonella and other organisms that cooking destroys. This is why the NHS lists raw shellfish among foods to avoid and why ACOG says avoid all raw and undercooked seafood. It applies to raw prawns in a ceviche, in sashimi, or undercooked in a stir fry.

Cold cooked prawns are a listeria risk, which is a different thing. Listeria grows at refrigerator temperature, so a food that was safe when it was cooked can become unsafe during storage. The Food Standards Agency lists cooked shellfish among the ready-to-eat foods in which listeria is more commonly found, and FSANZ names cooked ready-to-eat prawns specifically.

This is why the answer flips on temperature rather than on the prawn. Heat is the fix for both hazards.

What steaming hot means

The FSA's phrasing is to cook or reheat food until it is steaming hot right through. FSANZ puts a number on it: reheat food thoroughly until it is steaming hot at 75C. The FDA describes doneness for shellfish visually instead, since a thermometer is impractical in a prawn: shrimp and lobster flesh should be an opaque, milky white colour.

A prawn dropped into a boiling curry and simmered clears it. A prawn stirred into a warm pasta at the end does not. Prawns on a pizza that goes back into the oven clear it; prawns arranged on a finished dish do not.

The prawn sandwich, the prawn cocktail and the ring platter

These are the three dishes the guidance is really about, and all three are cold, pre-cooked prawns.

A pre-packed prawn sandwich is doubly covered: the NHS lists pre-packaged sandwiches and salads containing fish and shellfish among foods to be careful with, to be kept chilled and eaten before the use-by date, and the prawns inside are cold ready-to-eat prawns. It is not forbidden in the UK, but the instruction about heating the prawns is impossible to follow inside a sandwich, so the honest position is that it sits in the be-careful category and the safer choice is something else.

A prawn cocktail made at home from prawns you have cooked and cooled yourself is a smaller risk than one from a chilled counter, but it is still cold cooked prawns. A prawn ring or platter that has been standing at a party is the highest-risk version, because listeria multiplies during exactly that kind of warm standing time. The FSA advises eating ready-to-eat food within four hours of leaving the fridge, or two hours on a very warm day.

Frozen raw prawns cooked at home from frozen are the lowest-risk route of all, and they are cheap and quick.

Mercury is not the issue here

Prawns and shrimp are small, short-lived and low on the food chain, and they carry very little mercury. The FDA places shrimp on its Best Choices list, of which pregnant women can eat two to three four-ounce servings a week, and names shrimp among the fish it considers even lower in mercury for children.

FSANZ's mercury restrictions cover shark, billfish, orange roughy and catfish, not prawns. The NHS does not put prawns under any weekly limit; its shellfish note is that there are no maximum amounts recommended for white crab meat or other types of shellfish, and the only shellfish caution it gives on quantity concerns brown crab meat and cadmium.

So a plate of hot prawns does not count against your fish allowance in the way a tuna steak does. Prawns are useful protein and a source of selenium, zinc and iodine.

Scampi, tempura and takeaway prawns

Breaded scampi, tempura prawns and prawn crackers are all cooked at high temperature to order or in a factory, and are served hot. They are fine. The caveats around them are the ordinary takeaway ones: food that has been held warm rather than served hot, and cold garnishes and sauces.

Prawn toast, salt and pepper prawns and prawn curry are all cooked dishes. A cold prawn salad, a prawn sushi roll with cooked prawn, or a chilled prawn noodle salad are cold ready-to-eat foods; cooked-prawn sushi is not raw fish, but it is chilled ready-to-eat seafood, which is the category FSANZ and the HSE are cautious about.

If you have already eaten some

Cold cooked prawns eaten once are a low risk. Listeriosis is rare, and NHS advice on foods that should have been avoided is that a small amount, if you did not become ill, is unlikely to affect your baby.

Raw or undercooked prawns are more likely to produce ordinary food poisoning quickly. The NHS advice is to get help from 111 if you feel unwell after having food that should be avoided in pregnancy, or if you have had vomiting and diarrhoea for more than 48 hours.

For listeria, the window is longer. ACOG notes symptoms may appear as late as two months afterwards, and lists fever, chills, muscle aches, diarrhoea or upset stomach, with stiff neck, headache, confusion or loss of balance in more serious illness. Contact your midwife or GP the same day if any appear, and say what you ate.

Where guidance genuinely differs

The UK permits cold cooked prawns with a heating instruction attached. Australia and New Zealand list them as higher risk and ask you to choose freshly cooked instead. Ireland simply lists prawns among foods to avoid, which is the strictest position of the four and unusual in naming a cooked shellfish outright. The US restricts raw shellfish and refrigerated smoked seafood but does not name cold cooked prawns, so a US-based prawn cocktail is not on the FDA's avoid list.

The convergence point is straightforward and does not require you to pick a side: eat prawns hot, and every one of these guidelines is satisfied.