When Should You Lower The Crib Mattress?

white crib and mattress

Crib mattress height overview

As your baby grows you should expect to change the height position of the crib mattress, to make it easier for you to put them down and take them out of the crib, and more importantly, to ensure their safety.

This article will look at when you should lower the crib mattress, and when you should consider switching to a toddler bed and removing the rail.

Why it’s important?

Unfortunately babies and toddlers have accidents from time to time, and with domestic incidents, falling out of the crib is one of the more common occurrences.

According to a study from 1990-2008, there were around 180,000 injuries related to cribs, bassinets and playpens in the USA (around 10,000 per year). Of these, 83% involved cribs, and the most common reason was indeed falling out of the crib.

Therefore, parents should take careful consideration not only when choosing a crib, but also on a suitable crib mattress and how to adjust things as their child grows.

What are the regulations?

Considering the frequency of these crib related injuries, it’s understandable that countries have their own safety guidelines that parents should adhere to.

In the USA, the distance between the top of the mattress and the top of the sides should be between 20”-21” as a minimum.

In the UK, the regulations are similar. A cot should conform to British safety standards (BSEN716) and the distance between the top of the sides and the top of the mattress should be at least 50cm (19.7”) to prevent your baby from climbing out. The crib mattress should be no thinner than 8cm (3”)

When should you lower the crib mattress?

Most cribs these days, particularly the convertible types, have at least 3-4 adjustable mattress height positions so you can ensure your baby is safe and sound as they go through different stages, from only being able to lie down, to climbing out of the crib.

Here are some general guidelines:

boy sitting on floor in nursery

When should you raise it to the highest setting?

This should be for babies that can’t yet sit up by themselves.

In most cases, this will be for infants under 5 months i.e. newborns.

At this stage, you don’t need to worry about your baby climbing out of the crib, as they aren’t mobile, so the highest position is safe to use.

Also, it’ll make things easier for you and your back when you’re picking them up and placing them down in the crib (think of all the night feeds!) and you’ll be able to support their neck easier.

Once your baby starts rolling over and they’re able to sit up by themselves, it’s time to change the crib mattress height.

Some parents won’t need the highest setting because their baby might be in a moses basket and/or bassinet for the first few months before transitioning to a crib.

When is the best time to put it in the middle position?

All babies develop at different stages, but they can usually sit up between 5-8 months.

As soon as they can do this, you need to lower the crib mattress. The transition between sitting up and then trying to climb up can be faster than you realise, so you don’t want your baby to try and pull themselves up on the sides of the crib and fall out.

When should you lower your baby’s crib to the lowest setting?

You should lower the crib mattress to the lowest setting once your baby shows any sign that they are close to standing up, either by themselves, or by pulling themselves when they hold on to things.

It’s also a good idea to remove any unnecessary cushions or crib bumpers as your crafty little baby can stand on them to try and climb out of the crib.

This happened with my daughter one time. Her door was closed, and I thought she was asleep in her crib. Then to my amazement I heard her door handle turning. She’d managed to climb out of the crib by herself and land on some soft teddy bears to cushion the fall. I didn’t even hear anything!

It was at this stage that I knew we had to change things.

When should you get a toddler bed?

At this final stage, you might as well give up trying to contain your baby J

They need to be put in a toddler bed, and you’ll need to remove the toddler rail altogether.

You’ll need to do this once they can climb and/or if they’re around 90cm (35”) in height.

In either case you need to do it, otherwise you’ll have a similar situation to what I just mentioned above!

When should you lower the crib mattress? In this article you'll learn about the various stages when you should adjust the height of the crib mattress and ensure your baby's safety


How can you lower the crib mattress to the floor?

Not all cribs have this function, but with some tweaking, you can usually lower the crib mattress to the floor. In most cases you shouldn’t need it to be that low, but for your peace of mind, if your baby is not ready for a toddler bed and you still want the rail, it’s a viable option.

Just be careful that there isn’t a gap between the bottom of the rail and the top of the crib mattress, as your baby could get one of their limbs, or head stuck inbetween.

It’s important to note that many cribs have storage underneath and you’ll have to sacrifice this if you drop the mattress to the floor. However, they shouldn’t need to be at this stage for too long as it’ll soon be time to transition the crib into a toddler bed.

What is the recommended crib mattress height for a newborn?

Different countries will have slightly different regulations, but in the USA it should be around 21” from the top of the crib sides down to the top of the mattress. In the UK, it is 20”. However, it’s best not think in terms of distance from the floor, as your main concern should be if your baby can climb over the side of the crib or not.

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Author: Graham Scott

Graham runs the place around here. He likes making a "little noise" about all things to do with tennis and parenting. Check out his about page to learn more.

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