How to Choose the Best Cot Bed Mattress: Safety, Firmness, and Types Explained
Don't guess! Learn how to choose the best cot bed mattress for your baby. We explain UK safety standards (EN 16890), vital firmness levels, and compare foam, sprung, and natural types.
Designing your baby’s nursery involves many big decisions, but perhaps the most important one is choosing what goes inside the cot. The cot bed mattress is the foundation of your baby’s sleep, directly impacting their safety, comfort, and development during those crucial first years.
The NHS recommends a firm, flat mattress that fits the cot snugly. But with so many options—foam, sprung, pocket sprung, and natural—how do you know which one is the best cot bed mattress for your baby?
In this guide, we’ll cut through the confusion and walk you through the essential safety standards, ideal sizing, and the different mattress types available, helping you make the right choice for your little one.
Why the Cot Bed Mattress is the Foundation of Safe Sleep
Choosing the wrong mattress can be a safety risk. A mattress that’s too soft, too old, or doesn't fit correctly is dangerous. We recommend focusing on three core principles: firmness, breathability, and a perfect fit.
UK Cot Mattress Safety Standards: EN 16890 Explained
Your baby’s safety should always be the priority. In the UK, mattresses must comply with specific standards.
The key standard to look for is BS EN 16890. This certification replaced the old standard (BS 1877-10) and covers critical safety features, including:
- Firmness: Ensuring the mattress is firm enough to prevent the baby’s head from sinking in, which significantly reduces the risk of suffocation.
- Safety of Materials: Checking for hazards like loose components or chemical concerns.
- Durability: Testing the mattress for long-term use.
Always ensure the product description explicitly states compliance with BS EN 16890 for the ultimate peace of mind.
The Crucial Importance of Cot Bed Mattress Sizing
A mattress that doesn't fit the cot snugly leaves a gap, posing a serious entrapment hazard. Standard UK convertible cot beds require a 140×70 cm mattress.
Other cot sizes include
- 120 x 60cm - for mini cot/space saver
- 100 x 50cm - for mini cot/space saver
- 90 x 40 cm - for crib
The Snug Fit Rule: When the mattress is in the cot, there should be no gap wider than 3cm (or about one finger's width) anywhere around the edges. If there is, the mattress is too small.
Always check your cot bed manufacturer's specific guidelines to guarantee a perfect fit mattress.
Which Mattress is Best? Foam vs. Sprung vs. Natural
Once you've confirmed the size and safety standards, it's time to explore the three main types of cot bed mattresses:
1. Foam Mattresses (Polyurethane)
- Pros: Often the most affordable, lightweight, and easy to clean.
- Cons: Less breathable than other options, and lower-density foam can sag over time.
- Best For: Parents on a budget who need a simple, safe solution. Look for high-density foam for better support.
2. Sprung and Pocket Sprung Mattresses
- Pros: Very durable, excellent support, and the coil structure allows for better air circulation than solid foam. Pocket sprung mattresses (where each spring is individually wrapped) offer the most supportive and adaptable sleep surface.
- Cons: Heavier and often more expensive than standard foam.
- Best For: Parents seeking superior support and better longevity, especially if planning to use the cot bed until the toddler stage.
3. Natural Fibre Mattresses (e.g., Coir and Wool)
- Pros: Highly breathable, excellent thermal regulation (keeping baby cool in summer and warm in winter), and made from sustainable, natural materials.
- Cons: The most expensive option.
- Best For: Parents prioritising breathability, natural materials, and an eco-friendly cot mattress option.
Key Features: Firmness, Breathability, and Washable Covers
Regardless of the type you choose, look for these non-negotiable features, according to the NHS.
Firmness is Non-Negotiable: A firm baby mattress is crucial for reducing the risk of Sudden Infant Death Syndrome (SIDS). You should not be able to sink your hand or your baby's head into the surface.
Breathability: The mattress core and cover should allow air to circulate easily. Many mattresses now feature 3D mesh or breathable cores to maximise airflow.
Washable Covers: Accidents happen! A removable, machine-washable outer cover is essential for hygiene and extending the mattress's life. Look for water-resistant layers between the core and the cover.
Hypoallergenic: Helpful for babies with sensitivities or allergies, these materials resist dust mites and mould.
Your Questions Answered: Cot Bed Mattress FAQs
Can I use a second-hand cot bed mattress?
No. The Lullaby Trust and NHS strongly advise against using a second-hand mattress, even if it was used for a sibling. Mattresses change shape over time and may contain bacteria or mould that you can’t see, increasing the risk of SIDS. Always buy a new mattress for a new baby.
Do I need a waterproof cover for a cot mattress?
While many mattresses have integrated water-resistant panels, a separate waterproof sheet or protector is highly recommended. Place it directly under the main cotton sheet to keep the mattress clean and dry.
Should I flip or turn the cot mattress?
Most modern cot mattresses are single-sided and should not be flipped. However, some manufacturers recommend rotating the mattress head-to-toe every few months to promote even wear. Always check the care instructions.
Final Thoughts
Choosing the right cot bed mattress is one of the biggest steps you can take toward ensuring your baby has a safe and comfortable night’s sleep. Prioritise safety certifications, check the fit, and select a firm, breathable option that matches your budget and material preferences.
Sleep soundly knowing you’ve provided the safest foundation for your little one!
✨ Ready to complete your nursery?
👉 Shop our full range of Cot Beds and Mattresses at Prime Baby Gear