A guide for new parents on crib mattress height and when it should be adjusted according to babies milestones, skills and age.
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Babies and toddlers can get injured in their cribs, playpens and bassinets if the mattress height is not properly adjusted. According the Pediatrics Journal, there are 10, 000 injuries every year that are due to improper crib mattress height setups.
We do have an interesting guide on how to make your crib mattress softer, (spoiler, you shouldn’t) and used crib mattresses safety guidelines, but we haven’t covered the safety basics on crib mattress height.
We want to help parents understand when to lower the crib mattress and what setting to use according to the milestones that the baby hits.
Crib Mattress Height Guide
Babies climb out of cribs as early as 10 months of age. To keep things very safe, the Government has put together some guidelines to make sure the sleeping environment is safe for your little one as they become more mobile.
Most cribs have 4 levels where the mattress can sit at. Some cribs only have 3, which is ok and safe as well.
Crib mattress height will depend on your baby’s age, size and milestones. Newborns under the age of 5 months cannot sit on their own and can safely sleep on a crib mattress that sits on the highest setting. Once the baby can start to sit up on their own, the crib mattress should be lowered. Once the baby shows any signs of pulling up or standing, the crib mattress height should be in the lowest setting.
Level 1: The highest crib setting should be used from the newborn stage up until the baby can sit up on their own, usually around 5 months.
Level 2: This is the setting just below the highest mattress level and should be used between the ages of 5-8 months. This setting should stop being in use when the baby can pull themselves up to stand by themselves.
Level 3 -4: When babies show signs of being able to stand up on their own, this setting should be used. Some cribs have 3 and some cribs have 4 settings, use the lowest setting available when the baby begins to stand up.
Toddler Bed: When the baby can climb out of the crib or has reached a height of 35″, you should convert the crib into a toddler bed, or get a toddler bed for the baby room.
The minimum distance between the lowest mattress setting and the top of the crib rail is 26″. Crib mattresses are standard 5-6″ thickness which brings the top of the mattress to the top of the crib rail 20-21″. Which means that a toddler who is over 35″ tall can fall over head first and get a bad injury.
We don’t want anything to happen to our babies which is why we need to baby proof the home once baby becomes mobile, and changing the crib mattress height is part of the baby proofing checklist.
Cribs that were manufactured before 2011 are created to meet the safety standards that the CPSC has set out. It is a good idea to check the crib that you want to use in your nursery checks all the safety boxes prior to purchasing. These things are especially important to check if you are going to use an older previously loved crib.
Size: The crib slats should be no wider than 2 3/8″ in width and the bars should not be cracked or chipped. The top of the crib rail should be 26″ from the top of the mattress. The corner posts should be flush with the headboard and should not be able to catch on your baby’s clothing as they sleep.
Corner Posts Are Smooth: Corner posts on the crib should be flush with the end panels. If you have a fancy crib, ensure it has no rough edges and no fancy knobs or finials.
Secure Hardware: The hardware on the crib should be secured with no sharp edges that can injure your baby. The wood needs to be free of any cracks or notches that could snag clothing or hurt little fingers and toes. You should not use hardware from the hardware store with our crib. Always use the original hardware for the crib for ultimate safety.
Non-toxic Paint: Consider the paint that your crib has on it. Any crib manufactured before 1978 could have lead in the finish which is a serious health risk for your baby. Any crib that has cracked or peeling paint should be refinished properly before placing the baby for sleep.
Mattress Fit: The mattress should fit snug inside the crib. There should be no more than 2 fingers between the mattress and the crib. If there are more than 2 fingers that fit in that space, you might need a larger mattress. A proper crib mattress should be no thicker than 6 inches. For information on how to choose a crib mattress, visit this guide. If you are planning on purchasing a used crib mattress, please follow these safety guidelines.
Soft Bedding: When you have your baby in the crib for sleep, you should avoid having soft toys and bedding in the crib with your baby to avoid the risk of SIDS. You should not use soft crib bumpers in the crib. It is safer for the baby to have no crib bumpers than to have crib bumpers as crib bumpers could cause suffocation. Read our guide on how to make a crib mattress softer if you have further questions.
Drop Side Cribs: Do not use drop side cribs. They are simply unsafe and could cause harm to your baby.
Crib Mattress Height Guidelines
To recap, the highest crib mattress setting is for newborns up to 5 months of age, or until the baby can sit up on their own. The middle crib settings are for that in-between stage before the baby starts to pull themselves up to a standing position. The lowest crib mattress setting should be used when the baby starts to pull themselves up to a standing position. Lowering the crib mattress height to the lowest position will reduce the risk of fall and injury.(This post contains affiliate links. Our full disclosure policy is really boring, but you can find it here.)