When you’re a ravenous pregnant woman scouring the shelves at lunchtime for something that both takes your fancy and is safe to eat, the last thing you want is to decide on a tasty-looking lunch only to wonder whether you should actually be eating it.

Some ingredients in supermarket meals, like cheese, fish and egg, can make you ill or harm your baby, and when advice on ingredients isn’t to hand, you can’t find the answer online or the packaging doesn’t answer your questions, just buying a lunchtime sandwich or salad can seem like a hazardous venture.

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We checked out the NHS guidelines regarding the ingredients pregnant women frequently ask about from the lunchtime menus of leading High Street stores to see what is safe to eat and what isn’t. Here’s what they say.

Cheese

Cheese is probably the most queried of all the ingredients. There are so many different types – most of which are fine but a few of which should definitely be avoided.

Unsafe cheeses

Soft cheeses with white rinds

According to the NHS, pregnant women shouldn’t eat mould-ripened soft cheese (cheeses with a white rind) such as Brie, Camembert and soft goats’ cheese such as chevre. These are only safe if they’ve been cooked. Chevre is mould-ripened and has a white rind. Other types of goats' cheese without this kind of rind should be safe to eat, such as hard cheeses made with goats’ milk.

Blue cheeses
Similarly you should avoid soft blue-veined cheeses like Danish blue, gorgonzola and Roquefort. These, according to the NHS are also only safe to eat if they’ve been cooked.

Safe cheeses

Soft cheeses

Provided they are made with pasteurised milk all other soft cheeses are OK to eat. These include: cottage cheese, mozzarella, feta, cream cheese, paneer, ricotta, halloumi, goats’ cheese, cheese spreads.

[Read more: 15 things you should know about cheese]

Egg

Avoid foods that contain raw and undercooked eggs, such as homemade mayonnaise.

Cold cured meats

The NHS advises caution regarding cold cured meats in pregnancy. Many cold meats, such as salami, Parma ham, chorizo and pepperoni, are not cooked, they are just cured and fermented. This means that there's a risk they contain toxoplasmosis-causing parasites. Other cured meats, such as pastrami, are best avoided during pregnancy.

Fish

Tuna

According to the NHS, pregnant women should eat no more than two tuna steaks a week (about 140g cooked or 170g raw each), or four medium-sized cans of tuna a week (about 140g when drained).

You should also avoid having more than two portions of oily fish a week, such as salmon, trout, mackerel and herring.

Fresh tuna is an oily fish, so if you eat two fresh tuna steaks in one week, you shouldn't eat any other oily fish that week.

Tinned tuna doesn't count as oily fish, so you can eat this on top of the maximum amount of two portions of oily fish (as long as it's not fresh tuna or swordfish).

Shellfish

There is no need to limit the amount of white fish and cooked shellfish you can eat.

Always eat cooked rather than raw shellfish (including mussels, lobster, crab, prawns, scallops and clams). Cold pre-cooked prawns are fine.

Smoked fish

Smoked fish, including smoked salmon and smoked trout, is considered safe.

Sushi

The guidelines state that it's fine to eat raw or lightly cooked fish in sushi when you're pregnant, as long as any raw wild fish used to make it has been frozen first.

[Read more: Are pregnancy cravings real?]

Milk and yoghurt

Don't eat foods made from unpasteurised goats' or sheep's milk, such as soft goats' cheese.

All types of yoghurt, including bio, live and low-fat, are fine. Just check that any homemade yoghurt is made with pasteurised milk – and if not, avoid it.

High Street lunch options – safe or not?

We asked four of the leading high street lunch providers about some of the popular options on their menus which contain ingredients which are often queried during pregnancy. Their responses should give a clearer idea of what can and can’t be eaten at lunchtime when you’re expecting. While not all of the High Street stores are covered here, the advice for the ingredients is the same.

Pret A Manger

Brie, Tomato & Basil baguette – Not safe
Italian Prosciutto on Artisan – Not safe
Posh Cheddar & Pickle on Artisan - Safe
Salmon and baby kale superbowl  - Safe

Posh Cheddar & Pickle on Artisan

Pret A Manger say:

Is all of your cheese made with pasteurised milk?
Yes, all of our dairy products are made with pasteurised milk, including as of recently, our Italian Matured Cheese.

Are your cured meat products safe to eat?
The only cured meat product which isn’t safe is our prosciutto which is only cold cured.

Are your egg products made with pasteurised egg where necessary?
All our eggs and egg products are pasteurised.

Has the raw wild fish used in sushi has been frozen first?
We don’t use raw fish in our sushi. The salmon we use, which is smoked, has been frozen first.

Boots

Delicious 7 Inch Ham, Salami & Pepperoni Roll – Not safe
Delicious Smoked Salmon & Egg Sandwich - Safe
Nutritious Tuna, Grilled Peppers & Pea Sandwich on malted bread – Safe
Nutritious Egg, Slow Roasted Tomato & Watercress on tomato bread – Safe

Boots Egg Slow Roasted Tomatoe and Watercress sandwich

Boots say:

Is all of the cheese made with pasteurised milk?
The only cheese we use that is made with unpasteurised milk is Parmesan cheese. Parmesan is a hard cheese that is considered safe to eat by the Department of Health.

Are the cured meat products safe to eat?
The Department of Health advise “caution” with respect to cured meats such as salami and chorizo.

Are the egg products made with pasteurised egg where necessary?
Yes, we only use pasteurised egg and egg ingredients.

Has the raw wild fish used in sushi been frozen first?
Our sushi does not contain raw fish. Smoked fish such as salmon is used and considered safe to eat by the Department of Health.

Marks & Spencer

Brie, Grape and Cranberry Sandwich – Not safe
Ultimate New York Style Pastrami Sandwich – Not safe
Egg and Watercress Sandwich - Safe
Prawn & Vegetable Sushi Selection - Safe

Marks & Spencer say

Is all of the cheese made with pasteurised milk?
The majority of our cheeses are. We only have a few cheeses which are made according to the traditional recipe so use unpasteurised milk, however we label these clearly on the pack as containing unpasteurised milk.

Are the cured meat products safe to eat?
Cured meats are not necessarily cooked, they are cured/smoked. Current advice recommends being slightly more cautious including these in your diet when pregnant.

Are the egg products made with pasteurised egg where necessary?
All our egg-based products, eg custards, mayonnaise use pasteurised eggs.

Has the raw wild fish used in sushi been frozen first?
No raw fish is used in M&S sushi.

Waitrose

Waitrose Good to Go brie grape & chutney sandwich – Not safe
Waitrose Good to Go wheatberry, beetroot & goat's cheese salad – Safe
Waitrose Good to Go wheatberry, kale & feta- Safe
Waitrose Good to Go egg & smoked salmon sandwich - Safe

Waitrose Wheatberry Beetroot & Goats Cheese

Waitrose say

Is all of the cheese made with pasteurised milk?
Unless otherwise stated on pack all cheese is made with pasteurised milk.

Are all of the cured meat products safe to eat?
Because many cold meats are not cooked (they are cured and fermented) always check the 'on pack' instructions to see whether the product is ready to eat or needs cooking first.

Are the egg products made with pasteurised egg where necessary?
Unless stated on pack all eggs/egg products are pasteurised.

Has the raw wild fish used in sushi been frozen first?
All raw wild fish used in sushi is previously frozen.