Mattress Buying Advice for my Baby

When it comes to buying a cot mattress for your baby’s sleep, comfort and safety go hand in hand. That’s why Hannah Shore, our Head of Sleep Science, has created this expert guide to help you understand everything you need to know about choosing the right cot mattress.

Your little one will spend up to half of their first two years asleep, so where they sleep really does matter. The right mattress for a cot supports their development and helps create a cosy, secure space for restful sleep.

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How to choose a cot mattress

When you’re choosing a cot mattress for your baby, there are a few key things to keep in mind to make sure it’s the right fit for both comfort and safety. Here’s what I recommend looking out for:

1. Make sure it fits your cot properly

The first step is to check that your new cot mattress fits the cot snugly. In the UK, cot mattresses come in two sizes:

• Cot Mattresses - 70cm x 140cm (2ft 4in  x 4ft 7in)
• Continental Cot Mattresses - 60cm x 200cm (2ft  x 4ft)

Use a tape measure to check the internal dimensions of your cot before you make your decision. A cot mattress that fits well helps keep your baby safe by preventing any gaps or slipping. If it’s too big, the mattress can bend or get damaged, which reduces the level of support and comfort your baby needs.

2. Choose a firm and supportive feel

It’s really important to go for a firm, supportive mattress. This isn’t just about comfort - it’s for your baby’s health and development.

Soft mattresses might seem tempting and cosy, but they can allow your baby to sink in too much, which may affect airflow around their nose and mouth. A firmer mattress helps to reduce the risk of overheating and ensures that your baby’s whole body is properly supported while they grow.

3. Look for breathable materials

Since babies can struggle to regulate their temperature, a breathable mattress is a must. Breathable materials help promote airflow, drawing heat away from your baby’s body and making it easier for them to stay cool and comfortable during sleep.

Fibres like polyester and natural materials such as wool have tiny gaps between each strand, which allow air to move freely through the mattress. Bamboo and wool are also naturally antimicrobial, which means they help keep the mattress fresher by resisting the build-up of bacteria and other allergens - creating a healthier sleep environment for your little one.

4. Extra features to make life a bit easier

Cot mattresses often include features that not only support better sleep for your baby but also help make your life easier. Trust me - when you're changing sheets at 2 a.m., these little extras make a big difference.

Here are a couple I always recommend:

A removable, machine washable cover

Accidents happen, so being able to quickly zip off the cover and pop it in the washing machine can be a real time-saver.

A waterproof cover

Whether it’s built into the mattress or you choose to add a separate cot mattress protector, a waterproof layer stops liquids from reaching the mattress core. This keeps their sleeping environment more hygienic and helps the mattress last longer as they help to minimise day to day wear and tear.

These added features will be life-savers when the inevitable messes come along!

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What size is a cot bed mattress?

When it comes to cot mattresses, there are two standard sizes you are likely to encounter: a continental cot mattress size and a cot bed mattress.

A continental cot mattress is a little smaller, at 60cm wide and 120cm long. A cot bed mattress measures 70cm wide by 140cm long.

Size	Metric	Imperial
Cot Mattresses	70cm x 140cm	2ft 4in  x 4ft 7in
Continental Cot Mattresses	60cm x 200cm	2ft  x 4ft

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What type of cot bed mattresses can I buy?

There are several types of cot mattresses available, and each offers its own benefits. The right one for you will depend on your personal preferences and what you feel is best for your baby. Here are the three main types you'll come across:

• Foam cot mattresses
• Foam-free cot mattresses
• Sprung cot mattresses

Foam cot mattresses

Foam mattresses are a popular option - and for good reason. They’re generally firmer and more affordable than other types, making them a practical choice for many parents.

Benefits	Things to consider
Firm and supportive	Foam can retain heat
Often more budget-friendly than other options	They take longer to dry if there's an accident

Foam-free cot mattresses

These mattresses are often made from breathable polyester fibres, designed to regulate your baby’s body temperature and stay fresh all night long.

Benefits	Things to consider
Excellent breathability to help manage your baby’s temperature	They may feel slightly softer than foam, but still offer the firm support your baby needs.
Dry quickly after any spills or accidents
Naturally odour-free compared to foam options

Foam-free mattresses are a great choice if breathability and easy maintenance are your top priorities.

Sprung cot mattresses

Sprung mattresses contain coils or pocket springs to provide extra support. These are often layered with foam or polyester to keep the springs well-padded and safe for your baby.

Benefits	Things to consider
Offer strong support across the mattress	Can be more expensive than foam or fibre mattresses
Often very durable	May be harder to clean, depending on the mattress cover

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What type of cot mattress cover is best?

Choosing the right mattress cover is just as important as choosing the mattress itself. A good cover helps protect your baby’s sleeping environment, keeps things cleaner, and makes life easier for you too.

Waterproof cot mattress covers

For the best hygiene and mattress longevity, I recommend choosing a cover that’s both waterproof and machine-washable. Accidents are bound to happen, so a removable, zip-off cover that can go straight into the washing machine is a real time-saver - and a sanity-saver too!

Breathable cot mattress covers

It’s important that your mattress cover doesn’t just stop spills - it should also allow air to circulate. Look for breathable waterproof covers that combine protection with good airflow. 

Soft cot mattress covers

Your baby’s skin is delicate, so comfort matters. I’d recommend covers made from soft, knitted fabrics that feel gentle to the touch. These materials help create a cosy, calming surface for your baby to sleep on - without sacrificing the practical benefits of the mattress core.

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I hope this guide has helped you feel more confident about choosing the perfect mattress for your baby’s cot. A safe, supportive sleep surface plays a big part in your little one’s comfort and your peace of mind.

Explore our full range of cot bed mattresses, designed to give your baby the best start with safe, breathable, and baby-friendly materials.

And if you’re expecting, don’t miss our expert tips on sleep during pregnancy and mattress buying advice for parents-to-be. A restful night makes a big difference, both now and in the months to come.