The Complete Guide to Cots and Cot Mattresses
Published 12 Jan 2026
Decisions, decisions - where do I sleep my baby? Moses basket, crib, next-to-me crib, cot, or cot bed?
There's lots for new parents to think about. You'll be offered advice from all sorts of friends and family, midwives, and even more from the internet and AI!
All of these options have more positives than negatives, and the biggest factor is that your decision may be affected by your lifestyle and your purse. Let's investigate cots.
What is a Cot?
These are cots, not cot beds. A child can stay in one from around 6 months (when they can sit up unaided) to about 18 months to three years, then off to a single bed.
It's a different experience if you're transferring your baby from a crib to a cot versus going straight to a cot.
Choosing Your Mattress
There are lots of options here, and again your decision is influenced by price. Is it for one child, or do you want to use it for two or three? How long do you want them to stay in the cot?
Whatever you choose, think about firmness, support, waterproof protection, and hygiene. If you want this mattress to last, think about the manufacturer's guarantee.
Mattress Core Options
Fibre
This is the new kid on the block. Fibre has had a massive influence on baby mattresses because it's so very cheap.
The plus points of fibre: it's made from recycled plastic bottles, it's cooler than foam, and slightly more breathable. That's where the advantages stop!
Fibre is not as robust as foam and not as supportive or durable. It will dip and dent after a few months unless you're turning it very often - say a couple of times a week.
Press down firmly on a fibre mattress and it will leave a handprint. Do the same with good-quality foam and it will recover.
A fibre mattress is an OK buy for grandparents if their grandchild is only visiting a few times a year. If you're buying a fibre mattress for 24/7 use, you need to turn it often - at least twice a week.
Cheap fibre mattresses will only attract cheap covers. These mattresses are made to meet an attractive price point and will NOT have any waterproof protection. The marketing blurb may say "water resistant" - this is NOT the same as "waterproof".
Beware of Meaningless Marketing
While we're on the subject of meaningless tempting marketing words, you'll see the word "hypoallergenic" bandied everywhere. Here's an example I saw for a cheap fibre mattress: "Constructed with high-quality, nursery-grade hypoallergenic foam. Reduces allergies, provides excellent support and pressure relief for your little one."
Just meaningless twaddle! The word "hypoallergenic" is not regulated - anyone can use it! I know that mattress. I wouldn't put my dog on it!
Foam
Good-quality foam offers more comfort, support, and durability.
There are many different qualities of foam, and as you can imagine, the better the quality, the higher the price. Very few retailers will proudly disclose the quality of the foam they're using.
Foam is measured in two basic ways:
- Density: The weight per cubic metre in kilograms. Basically, 20kg will be poor and 33kg will be very good.
- Hardness: The amount of weight in Newtons it takes to squash 10cm depth of foam to 4cm depth. Poor foam quality will squash with 120 Newtons; good foam quality will need 130 Newtons or more.
Put that together: 120/20 will be poor foam, and 130/33 will be good-quality foam. You're now a foam expert!
Foam with Springs
This is becoming the better norm for quality cot mattresses. Please avoid old-fashioned Bonnell springs and go with pocket springs. The pocket springs you want are ones joined on length AND width, not just length.
The British Standard for a pocket sprung mattress is 10cm deep; the springs are 6cm deep. Therefore you have 2cm depth of foam either side to cover the pocket springs - that's all! If the quality of foam is poor, the foam will dip or dent in less than a year.
Foam as a product does not like HEAT, WEIGHT, and DAMP - that's exactly what a baby is! Poor-quality foam will sink and dip, give reduced support, and have a shorter lifespan.
Coir and Wool
If a company is manufacturing this product, price is not at the forefront of their mind. Their focus is on quality, comfort, safety, and durability. This natural mattress will have a firm, quality base with quality wool either side, held in with stockinette, then waterproof protection and a quality machine-washable cover.
Look out for Outlux or Moulton fabric for a natural mattress. This cover is two layers of cotton with PU sandwiched in the middle, guaranteeing waterproof protection.
Mattress Covers
First, look for waterproof protection in the mattress design. If it's not there, you'll need to buy a waterproof protective cover.
Think about putting the waterproof protection under the cover and over the mattress base - then you get the breathability of the cover.
Look for a mattress with a welcoming cover like padded microfibre, CoolMax backed with a spacer fabric, or bamboo.