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When to Lower Crib Mattress for Babies? [Guide per Age]

When to Lower Crib Mattress for Babies

Parenting is rife with decisions and challenges that are entirely new to you. These choices can be challenging to manage, and with so many options available to you, it can be overwhelming.

One of the many decisions is when to lower your baby’s crib mattress.

The baby is getting bigger, and you want to know when is the best time to change the crib’s mattress height.

Crib safety can be complicated and confusing. It’s not as easy as simply buying a crib, placing your child in it, and calling it a day.

Keep reading to find out when and why you should lower your baby’s crib mattress.

Table of Contents
Table of Contents

When Do I Lower the Crib Mattress Height?

Here is an easy-to-follow guide for choosing which crib setting to use and when to lower the crib mattress at certain stages or changes in your baby’s life.

Stage 1

Stage 1

This stage is for newborns who are still unable to push off or roll over. At this stage, the baby crib mattress height should be set to the highest possible setting.

As long as the baby is of newborn age, and they still cannot lift themselves, it’s baby-safe to place the crib mattress at the highest possible setting.

Having the crib mattress in this position means it is closer to you. There is no risk of the baby falling out, and it will be easier on you when placing your child into their crib or when lifting them out.

There will be less risk of:

  • Needing to bend over too far
  • Waking or disturbing the baby, or
  • Not properly carrying their necks when placing them in or lifting them out

Remember, though, that as soon as your baby reaches independent mobility, including sitting up, getting on their hands and knees, or rolling over on their own, IT’S TIME TO LOWER your baby’s crib mattress setting.

Keep in mind that in the United States, the minimum distance between the top of the crib rails and the top of the lowest crib mattress support is 26 inches.

Stage 2

Stage 2

Once the baby sits up on its own, it’s time to lower the crib mattress setting. At this point, the baby’s crib should be moved to the middle height setting.

Stage 2 is for babies who can sit up, push onto their hands and knees, and roll onto their bellies. Usually, this stage starts at the age of 5 to 8 months old.

Once the baby has started rolling on their own, they will start pushing themselves up to their hands and knees, preparing to crawl.

You will need to lower the crib from the highest position for your baby’s safety. It could be dangerous since your baby may pull themselves up to standing position at any time.

This is also the stage where teething starts to happen, so don’t be surprised if your baby starts knawing at their cribs.

You can take a look at our guide on what to do when your baby starts chewing on the crib for the proper safety guidelines.

Stage 3

Stage 3

This stage is for babies and young toddlers at an age where they are able to sit up and show signs of attempting to achieve a standing position.

At this stage, you will need to lower the child’s crib mattress to the lowest possible setting for the crib’s mattress height.

Having the baby’s crib mattress height at the lowest crib setting makes it more difficult for your baby to climb out of the crib and greatly reduces the likelihood of them falling out.

At this level, any crib bumpers should be taken out as well because the baby might be able to use them as leverage to climb out of the crib.

Stage 4

Stage 4

At this level, where the child is likely to climb or is 35 inches or taller, you should no longer be using a baby crib. Instead, the child should be using a toddler bed.

You can start by introducing them to a toddler mattress before transitioning to the full toddler bed. The main difference is that it is not as firm as a baby crib mattress.

How to Lower the Crib Mattress Height

How to Do It

When doing this, make sure to follow the manufacturer’s instructions. Adjusting mattress height is usually straightforward enough and requires only a few steps.

  • Start by choosing the height you want to use.
  • Before setting up the baby’s crib with screws, decide on this already so that you can set it up faster.
  • Remove the bedding, such as crib sheets and the mattress protector. If you are adjusting an already made crib, you will need to remove the screws and lower the mattress to your desired setting.
  • When you return the screws to the new setting, ensure that the crib and mattress are stable.
  • Finally, reset the mattress. Replace the crib sheets and the mattress protector at the new level.

What Is the Right Baby Crib Mattress Height?

Based on federal crib regulations, the right height should be:

A MINIMUM distance of 26 inches between the top of the mattress and the top of the crib side rail. Take note, this also includes the height or thickness of your mattress.

Allow us to explain further.

  • If you have a 6-inch thick mattress, the remaining distance between the top of your mattress and the top of the crib side rail should be 20-inches. This varies, depending on your baby’s age and size.
  • If your baby is taller or you want to be extra safe, you can increase the minimum distance to 30 inches or more. It will need to be adjusted once your baby is able to sit and stand or as soon as they become mobile, which comes sooner than you may think.

Because bassinet injuries and falls from improper crib height are so common, the American Academy of Pediatrics has placed regulations for proper crib safety and height.

  • The correct crib height ensures that the baby does not “escape” from their crib once they are mobile. These guidelines were made for babies below the height of 35 inches.
  • If your child is 35 inches or taller, you will already need a toddler bed, not a crib.

The Importance of Crib Mattress Height


You’ll find several kinds of categories and types of cribs for children.

Although most baby cribs have adjustable mattress level features, have you ever thought about why this is important?

Your child’s crib mattress height is actually more important than most parents think.

To put this idea into perspective, US emergency rooms treat on average nearly 10,000 zero- to two-year-olds every year.

According to a study published in the journal Pediatrics, more than 80% of these injuries involve cribs.

Although some of them are due to crib mattress support and support of the baby, a lot of these crib-related injuries are due to babies falling from a crib, playpen, or bassinet.

This fact means that several emergency room visits could be prevented simply by applying the proper crib mattress height for our babies.

Why Raise the Crib Mattress Height?

At this point, knowing there is such a high risk of your baby falling out of their crib, you may be wondering why should I even adjust the crib mattress at all?

Shouldn’t I just set it to the lowest height setting possible to ensure they don’t climb out of their cribs? As tempting as that may be, here are some reasons why that can be problematic.


The first reason is that placing the mattress at the lowest crib mattress setting may make it more difficult for you, the parent.

Imagine that you are about to put your newborn into their crib, which you have set to the lowest level setting. Then imagine not being able to reach the mattress to lay down your baby.

  • Average to shorter mothers or fathers may have difficulty placing a newborn baby into their crib if the mattress is set to the lowest setting.
  • There is a danger of the parent falling into the crib while setting the baby down if the mattress has been placed too low.
  • Even if you are a tall parent, it can still pose a challenge because bending over that low can cause one to have pain in the lower belly, especially for a new mother.

For the sake of ease and safety for yourself and your baby, a higher mattress setting may be a better option for a newborn and a mom who has just given birth.

Baby Has Acid Reflux

The second reason is Gastroesophageal reflux disease or simply reflux, which can make sleeping in a flat position on their backs uncomfortable for the baby.

When the baby lies flat, the acid from their stomach fluids can rush up into their esophagus, and it will cause a painful burning feeling in their throats.

The reflux can also cause your baby to spit up or vomit, making it difficult not only for them but also for you to get a good night’s rest.

As much as possible, we want to avoid causing any unnecessary strain or discomfort for our children with reflux. It can be as simple as adjusting the crib mattress position to keep the acid down.

Baby Has Congestion

Finally, if your baby is experiencing allergies or colds, they may become congested.

This means there is mucus buildup in their sinuses and becomes difficult for them to breathe.

Similar to reflux, if the baby is lying in a flat position on their backs, the congestion can stuff up their sinuses more, making it even more difficult for them to breathe and sleep through the night.

If you adjust the mattress or bed position and safely place it on an incline, your baby will be able to sleep and breathe better.

Baby Sleep Safety Guidelines

Sleep Safety Guidelines

We always want to keep a baby safe! The infant stage is always going to be a little more of a precarious time in a child’s life.

For the simple reason they are entirely dependent on their parents, infants need to be cared for with the utmost responsibility.

From the kind of crib to the proper crib mattress, even the most suitable crib height, there are so many things a parent must keep in mind to ensure their baby sleeps safely and soundly.

For example, you should also make sure you get a non-toxic crib for your baby!

We found a couple of guidelines to remember and follow to ensure their safety and relaxing sleep environments.

These safety tips will help prevent your baby from suffering from sudden infant death syndrome, which is the sudden unexplained death of babies below a year old.

Share a Room

Room sharing is HIGHLY recommended for a parent with newborns at home. This way, at least one parent can ensure their children are always safe while they sleep in their toddler bed.

Place the baby in a separate sleeper such as a bassinet or crib with the proper crib mattress but make sure it’s in the same room you are sleeping in.

Make Sure They Sleep on Their Backs

Before a baby is able to turn or roll themselves onto their stomachs on their own, make sure they sleep on their backs. This is one of the best safety tips we can give you!

This will prevent the likelihood of sudden infant death syndrome. Ensure they are sleeping comfortably on their backs and, if needed, raise the crib mattress to a comfortable angle.

Once they can turn themselves over and back on their own, it’s less necessary to flip them onto their backs again.

Avoid Sleep Positioners

Although they may seem useful and like a good idea, sleep positioners are somewhat unnecessary.

They may pose a risk of the baby turning over and having their face pressed up against the sleep positioner, suffocating the child.

Avoid Any Crib Extras

As tempting as it may be to place stuffed toys, extra pillows, blankets, and any other additional features into the crib for cute sleep environments, this may not be the safest idea.

To ensure your baby’s safety, you should try to keep the inside of the crib as simple and minimalistic as possible.

This way, you will prevent the child’s risk of rolling over and suffocating on one of the toys or pillows placed inside the crib.

Final Words

Final Words

Hesitating to lower a crib or not understanding how it is essential at all is completely understandable. With all the different information available online, it can become a tad confusing.

However, hopefully, now that you know when and why to lower a crib, you should be able to move into the further stages of your kids’ life more easily with this new information.

If you are still unsure, contact an expert or get a second opinion. As parents, you always want to err on the side of safety for your babies.

And should you need a reliable mattress for your little one, we highly recommend the Naturepedic brand. Check out our article on the Different Kinds of Naturepedic Mattresses for good options.

For a list of all the things you need for your baby, check out our Complete List of Baby Furnitures.


November 13, 2022 – minor content edits

June 27, 2022 – minor content edits

August 5, 2021 – added 1 new article link

July 23, 2021 – reviewed and updated article links

About the author

Angelica Graham

A few years ago, Angelica found out about all the plastic and toxic ingredients that got into most children’s products. And this worried her to no end. Because of this, she began to research what the best ingredients and materials were for children and made it her mission to share this information with other mothers.