When To Lower Crib Mattress Height

baby crib mattress set to highest position

Your little one is surely growing quickly. Have you noticed him doing new things each day? Adventurous and curious – as they start to move around the ouchies and booboos begin to add up.

But while small bumps and bruises are inevitable, a fall from a crib should never happen. That’s why it’s important to be aware of the milestones that signal its time to lower the crib mattress height.

It feels like I just moved my daughter into her new crib, but she is already holding the rails….getting ready to start pulling up.

Which got me thinking…..Is it time to lower my baby’s crib mattress height already?

Uggghhhh…..another thing to add to my to-do list.

Buttt…for safety reasons, I certainly don’t want to delay this important task. I definitely don’t want my baby to end up in the emergency room with a head injury.

So by sharing this article, I hope I can help keep your baby safe and allow you to enjoy more of motherhood.

Enjoy Mom Life is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission at no cost to you.

Safety First

baby outgrew crib

As new parents, your baby’s safety is your #1 priority. Here are some crib safety facts:

  • According to the AAP (American Academy of Pediatrics), falls are the most common crib-related accidents
  • In order to minimize the risk of falls, it is important that parents know when to lower the baby’s crib mattress height
  • According to a 19-year study, falls from cribs often lead to head and neck injuries

To reduce the risk of injury from cribs:

  • Make sure your crib is not outdated – older cribs manufactured prior to 2011 are unlikely to meet current safety guidelines
  • Make sure your crib has not been recalled, by visiting the CPSC (Consumer Product Safety Commission) website
  • Lower your baby’s crib mattress as they grow…more on this below

Crib Safety Tips

The following items are no longer considered safe:

  • Drop-side cribs
  • Cribs with missing or broken slats
  • Crib bumpers aka bumper pads
  • Loose blankets – loose blankets are thought to pose a suffocation risk, use a sleep sack instead

Baby Crib Heights

Most cribs offer 2-3 height options. During the first year of your baby’s life, your baby’s crib mattress should be moved to the lowest height. These are the most common positions:

Highest Crib Setting

highest crib mattress setting

The highest setting is similar to a bassinet’s height. It is designed for the smallest babies that don’t roll or sit up.

This setting does not have high walls – which can become a safety hazard when your baby becomes mobile.

Middle Crib Setting

crib mattress in mid position

The middle setting generally places the mattress height at the midpoint between the top and bottom of the crib.

Lowest Setting

crib with mattress in lowest setting

This height setting is the lowest point where you can set your crib mattress. It is the deepest and hardest-to-reach position (for short moms like me).

Do I Have to Lower the Crib Mattress Height?

baby crying in crib

If you are starting at any level other than the lowest level then YES, you will need to adjust your baby’s crib mattress height as they grow.

However, if you don’t want to deal with having to lower the baby’s crib mattress, then it’s ok to set it at the lowest height from the beginning. The lowest height is safe for all babies until they have outgrown their crib.

The disadvantage to placing small babies to sleep at the lowest mattress level is that it can be hard to lay them down to sleep without waking them up. This is especially true if you are short….yes, short girl problems.

I literally still struggle to put my daughter down in the pack-and-play or crib without her waking up!

When To Lower Crib Mattress Level

This is a general guide, be sure to refer to your crib manufacturer’s instructions for when to adjust the mattress height. Always use your best judgment.

For your baby’s safety, it’s better to lower the baby’s crib mattress before they reach the milestones.

Highest Crib Setting

crib with mattress at highest setting

The highest level is best for newborn babies that are immobile, which is usually up to about 4 months of age.

You will want to lower the bassinet height setting when your baby reaches any of the following milestones:

  • Can rollover
  • Can push up on all 4s

Babies generally meet these milestones around 4 months of age.

The following are signs your baby is at high risk of injury. Do not let your baby sleep with the mattress at the highest setting if they can do any of the following:

  • Your baby’s head can look over the top of the railing
  • Your baby can put an arm or a leg over the crib railing
  • Your baby can crawl
  • Your baby can sit

If a baby is too big for a bassinet, then they are too big to sleep with the mattress at the highest position. So, if you are transitioning from bassinet to crib, you will want to set the mattress lower than this setting.

Middle Crib Setting

The middle setting refers to the mattress height at the midpoint between the top and bottom of the crib.

If you are transitioning from bassinet to crib, this is most likely a good height for your baby’s crib mattress.

This setting is ideal for babies who are rolling, sitting, and crawling.

This crib setting is safe to use until your baby can:

  • Pull up to a standing position
  • Walk
  • Look over the top of the crib side rail

Babies will generally meet these milestones around 9 months of age. You want to move to the lowest level when your baby meets any of these milestones.

Lowest Crib Setting

crib with mattress at lowest setting

This setting is the lowest position where you can set your crib mattress. It is the deepest and hardest-to-reach position (for shorties like me).

This setting is ideal for babies who can pull up, stand or walk.

It’s the safest position for older babies – but soon enough they will outgrow their crib. Once your child is ready to transition out of the crib you can consider a toddler bed or floor bed.

The following are signs its time to transition out of a crib

  • Your baby’s nipples reach the top of the crib rail
  • Your baby tries to crawl over crib rail

Keep in mind:

  • Most cribs are safe to use until about 2 years of age
  • But, if your baby is 35 inches tall, then it’s time to transition to a toddler bed
  • Also, be sure to check your cribs weight limits (yes cribs have weight limits!)

How To Lower Crib Mattress Height

Refer to your manufacturer’s instructions for details specific to your crib.

  1. Place your baby in a safe space – away from any small screws and bolts
  2. Remove the baby’s mattress and all the crib bedding
  3. Unscrew the mattress support
  4. Move mattress support into the new position
  5. Screw the mattress support back into place
  6. Check the crib entirely, and tighten any loose screws
  7. Replace mattress and bedding

What’s Next?

So your muchkin has outgrown their crib?!

That’s exciting. Next comes another big transition: the toddler bed.

But, if your child is scared of sleeping up high, you can also consider a floor bed.

Now that your baby is no longer confined to a crib, you want to be sure that your baby’s room is fully baby proofed and that there is no risk of falling down the stairs.


When to lower the crib mattress will be different for every child, because they will meet their milestones at different times. If you are unsure if you should lower the mattress height, remember it’s better to be safe than sorry.

If you noticed your baby has met some of the milestones mentioned above, then now is the right time to lower your baby’s crib mattress.

Thanks for reading. I hope this article gives you peace of mind knowing your baby is sleeping safely.

Follow us on Facebook to stay up to date on our latest blog posts!

You may also enjoy:

Do Cribs Expire? Crib Safety 101

How Much Weight Can A Crib Hold?

When Is A Baby Too Big For Its Bassinet?

How to Transition from SNOO to Crib (Without Losing Your Sanity)

How To Transition Your Baby From Bassinet To Crib

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top