Which? Don't Buy cot mattresses

Don't put your baby's sleep at risk or waste your money on a terrible cot mattress.  

A Don't Buy mattress won't stand up to night after night of wriggly sleep, baby sick and nappy leaks. Or, it will fail to give your baby the vital support he or she needs in those early days and as they grow. 

Our tough lab tests have uncovered 15 mattresses which may let you down. We highlight the cot mattresses you should avoid.

See our round-up of the best cot mattresses to find out which are firm and supportive, easy to clean and resistant to leaks

What makes a Don't Buy cot mattress?

Our tests uncover what we consider to be the best and the worst. If a product performs so poorly that we think you should avoid it, we call it a Don't Buy. We've tested 15 cot mattresses that we've named Don't Buys based on their performance under our independent safety tests.

Our safety tests replicate those in the current cot mattress safety standard, BS EN 16890:2017 + A1:2021. 

Our independent testing of several cot mattresses revealed as follows:

There are three serious safety issues we commonly see:

Suffocation risk 

If the top layers of the mattress are too soft and your baby accidentally rolls on to their front, their face could sink into the mattress. This is a concern with babies aged 4-12 weeks, when they are typically able to roll over from their back to their front. 

Rolling from front to back requires more strength, and in some cases a baby may not master this skill until they reach around six months old. That's why we check the firmness of the mattress when new and also after our durability tests, to see if it poses a suffocation risk. 

The Mamas & Papas Luxury Twin Spring Cotbed Mattress failed after durability the tests caused the top layer to sag in a few places. 

A spokesperson from Mamas & Papas said: 'Every Mamas & Papas product complies with all relevant British and EU safety standards and is tested in an independent UKAS accredited lab to the required standards. We strongly disagree with the Which? findings…Our customers can be confident that these products meet or exceed the current required safety standards.’

Entrapment risk 

If a mattress is too small to fit snugly into a standard cot bed, it creates a gap between the mattress and the frame where your baby could get their arm or leg stuck, and they may be unable to remove it. This may be dangerous if your child gets stuck while lying on their front. 

In addition, some mattress covers shrink after washing, which can compress the mattress and reduce it's size so it no longer fits snugly. This is a potential injury risk as there's an unsafe gap where your child can trap his or her limbs.

Our independent testing of several cot mattresses revealed as follows:

The Snüz Surface Duo Dual Sided Cot Bed Mattress and John Lewis Pocket Spring Cotbed Mattress were found to be too short and left gaps between the mattress and the bed frame. The iStyle Mode Baby Toddler Cot Bed Mattress wasn't big enough when new and it shrunk further after the cover was washed leaving gaps.

The Mother & Baby White Gold Anti Allergy Pocket Sprung Cot Bed Mattress, the Naturalmat Coco Mat and the Naturalmat Latex Mat, the Cuggl Pocket Spring Cot Bed Mattress cover and the Mamas & Papas Premium Pocket Spring Cot Bed Mattress cover also shrank after washing, which compressed the mattress and could result in gaps between the mattress and the frame.

The Obaby Pocket Sprung Cot Bed Mattress is too large – it exceeds 140 x 70cm, which means it may not sit flat in the cot bed, providing an uneven sleeping surface for your child when it needs to be flat as required by the cot mattress safety standard, BS EN 16890:2017 + A1:2021.

A spokesperson from Snuz said: ‘We cannot comment on why [Which?’s] results differ from our consistent pass results at a fully accredited UK laboratory.’

A spokesperson from John Lewis said: ‘Our products undergo independent and rigorous testing, and our Pocket Spring Cotbed Mattress passed all safety standards, including entrapment hazard tests.' 

A spokesperson from Mother & Baby (CuddleCo) said: ‘Any customers who have washed the cover at 60°C can email our customer services team at customerservice@cuddleco.co.uk if they have any concerns.’

A spokesperson from Cuggl said: ‘Neither our technical files nor testing data show the same issues that Which? has identified.’ 

A spokesperson from Naturalmat said: 'Safety has always been paramount to us. In September 2024 when these tests were carried out the Coco and Latex Mats did not meet EN 16890:2017+A1:2021, however since November 2024 we now comply with these standards. We met this standard by removing the zip pull.'

Regarding its Premium Pocket Spring Cot Bed Mattress, a spokesperson from Mamas & Papas said: 'We're highly surprised and dispute the findings of this review conducted by Which?. Safety is the prime consideration for Mamas & Papas and we ensure all our products are tested to and comply with all European safety standards and UK regulations.’

A spokesperson from Obaby said: ‘Our pocket sprung mattress is tested to BS EN 16890:2017 from an accredited FIRA test centre. Customer’s health and safety is our top priority, and we ensure that our products conform to all standards and safety measures which, following the industry standard is done every two years.’

Choking hazard 

We check how easy it is for curious toddlers to access the inner filling of the mattress, as well as the zip pull, as both can easily be swallowed and become a potential choking hazard.

Our independent testing of several cot mattresses revealed as follows:

The Ickle Bubba Fibre Cot Mattress zipper detached in our tests, and it was easy to access the mattress filling during our testing. The zipper pull tab on the Mother & Baby White Gold Anti Allergy Pocket Sprung Cot Bed Mattress broke off during our testing and this was the case for the Mamas & Papas Premium Dual Core Mattress, Mamas & Papas Luxury Twin Spring Cotbed Mattress and Mamas & Papas Essential Fibre Cot Mattress, as well as the Naturalmat Coco Mat and Naturalmat Latex Mat.

The Obaby Foam Mattress we tested had no non-removable inner cover, and it was easy under our testing to access the filling materials. The core of the Obaby Pocket Sprung Cot Bed Mattress, the Snüz Surface Duo Dual Sided Cot Bed Mattress and the iStyle Mode Baby Toddler Cot Bed Mattress were also too easily accessible under our tests.

The zip pull tab on the outer cover of the Mamas & Papas Essential Spring Cotbed Mattress broke and the net-like inner cover was torn, so the core was accessible. The zip pull detached on the Mamas & Papas Luxury Twin Spring Cotbed Mattress. Separately, the outer cover has an opening on the side that has the potential for your child’s limb to get stuck. 

A spokesperson from Ickle Bubba said: ‘We are satisfied our mattresses are compliant and safe for market requirements and general use.’ Ickle Bubba states that it is assessing Which?’s feedback and considering how to improve the product moving forwards.

A spokesperson from Naturalmat said: 'Our mattresses have an inner cover as well as an outer washable cover, and if our washing instructions are followed correctly the cover should not shrink and the size of the mattress will not change. We also offer replacement covers should they be required.'

A spokesperson from Mamas & Papas said: ‘All Mamas & Papas products comply with all relevant British and EU safety standards and are tested in a UKAS accredited lab to the required standards.’

Regarding its Foam Mattress, a spokesperson from Obaby said: 'Obaby strongly disagrees with the findings presented by Which?. We ensure the safety of our products by diligently adhering to all necessary safety tests and complying with required standards…. We independently retested the mattresses, and they confidently passed the required tests, backed by certification.’

A spokesperson from Snuz said: ‘We cannot comment on why Which? results differ from our consistent pass results at a fully accredited UK laboratory.’

How we uncover the best and worst cot mattresses

Which? has reviewed the latest cot mattresses from all the big brands including Ikea, Cuggl, Mamas & Papas, John Lewis and Silentnight

Our in-depth testing means we can recommend those cot mattresses that are firm, breathable and will help to keep your little one cool. Plus those that last through tough durability tests, and support your baby as he or she grows. 

• Body support Your baby grows a lot in the first few years of his or her life, so it's crucial that the mattress you buy provides support for your little one's body as a baby and as a toddler. We use dummies of different weights, simulating children of different ages, to show how well each mattress supports children, from newborn to the age of five.
• Durability A firm mattress is a must with a newborn, and how well it will last is something you can't tell in a shop just by looking. Our tough tests simulate two to three years of use on every cot mattress to see how each one holds up to wear and tear.
• Staying clean and dry A cot mattress with a cover that's easy to whip off in the dead of the night when little (or big) accidents occur, and still looks as good as new after many spins in the washing machine is worth looking out for. We assess for fiddly to remove mattress covers that are going to shrink over time and fabric that will end up bobbling, and take points off for any which could give you sleepless nights.