Why Are Bassinet Mattresses So Thin? (And Should You Replace It?)

The short answer to the question why are bassinet mattresses so thin and hard is because of newborn sleep safety.

But there’s more to it than that.

Why Are Bassinet Mattresses So Thin and Hard?

Bassinet mattresses are thin because a thin and firm (not hard) bassinet mattress is safe for your baby.

A thick, soft, plush mattress is a disaster waiting to happen.

Newborns can’t move around, let alone turn their heads from side to side. So they can sink into a thick mattress and if they’re stuck and can’t turn their heads away, it can lead to suffocation and even SIDS.

The dents, dips, and sags in a thick and soft mattress can also cause some gaps between the mattress and the bassinet, which can create an entrapment hazard.

Hence the federal government issued a ruling to establish safety mattress standards.

The AAP also specifically mentioned using a firm, flat mattress plus a fitted sheet for sleep safety purposes.

But My Baby Looks Uncomfortable In the Thin, Hard Mattress

We as adults might find it extremely uncomfortable to lie down on a thin and hard mattress. But it doesn’t work that way for babies and even toddlers.

There’s a reason why most young children can sleep anywhere, even in the most awkward, hilarious positions. Because some can. Case in point:

It might seem unbearable to sleep on a thin and hard mattress, but it’s totally fine for your little one.

Bassinet mattresses are not supposed to be thick and should feel firm, for your baby’s safety.

Bassinet Mattress Buying Guide

Ask the manufacturer

Most companies provide bassinet mattress replacements, but if you can’t find any, ask if they can recommend another alternative.

Firm and Thick

It’s a non-negotiable, must-have feature.

Must Fit

Get the correct dimension by looking at the manufacturer’s website, or instruction manual or asking them directly via email or their social media channels.

Some bassinets have oval shapes so pay attention to their shape and sizes, to get the right mattress that can fit properly and snugly in it.

Waterproof Sheets

Consider also the ease and convenience of getting some mattress sheets. Is it easily available online? Or is it expensive, is it always sold out, is it hard to find?

Having a waterproof mattress sheet is also best to have but look for something that’s less crinkly. As you don’t want your baby waking up constantly because their mattress sheet is making some noise.


A bassinet that meets and even exceeds European and US safety standards, that is GreenGuard™ Gold certified, with fabrics and sheets that are certified Oeko-Tex® Standard 100 Class are ideal to have for their baby-safe and non-toxic qualities.

Can I Replace a Bassinet’s Mattress?

The CPSC recommends using the provided mattress that comes with the crib, pack ‘n play, and in this case, the bassinet. 

It’s not recommended to use another mattress as it might not be the right fit, making it a safety hazard.

However, if there’s really an urgent need to replace the bassinet’s mattress, (eg. 2nd hand and worn-out, defective, destroyed by pets, or even by your baby’s mess), scroll down below for tips on what to look for in a bassinet mattress.

Can I Use a Second-Hand Bassinet Mattress?

For hygienic and safety purposes, I strongly recommend NOT using a second-hand bassinet mattress. 

It can still be of excellent quality, it can still feel firm, and it can be the right size, but the use of second-hand mattresses can significantly increase the risk of SIDS.

Plus, you don’t know what that mattress has been through.

Babies can spit, vomit, drool, pee, and worse in their sleeping area. Pets could have slept in it, and other items might have tainted it. Stains, dirt, bacteria, and whatnot can still stay on the mattress so using a second-hand mattress is a big NO.

FAQ: Bassinet Mattresses Too Hard

How thick should a baby bassinet mattress be?

The bassinet mattress should be no more than 1½ inches thick. A thicker mattress is a suffocation hazard.

Are bassinet mattresses supposed to be thin and firm?

Yes, bassinet mattresses are supposed to be thin and firm. A thick and soft mattress is a risk factor for suffocation and SIDS.

Final Thoughts on Why Are Bassinet Mattresses So Thin and Hard

I understand doing everything to make your baby snug and comfy in their bassinet but there’s a reason why a bassinet mattress is thin and hard.

Don’t stack 2 mattresses, don’t put or wrap anything soft on the mattress, and just basically, leave the bassinet mattress alone.

As long as safety sleep guidelines are followed, your baby will be fine sleeping on it.

I hope you find our “why are bassinet mattress so thin” useful.

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