Crib Mattress Height for Newborns: Why the Highest Setting

Why newborns use the highest mattress setting

The highest mattress setting places the mattress close to the top of the crib rails. This position allows a parent or caregiver to reach the baby without bending deeply, making it easier to lift the newborn in and out. The setting is standard for the first months when the baby is small and not yet able to sit up or move around.

The highest setting also reduces strain on the caregiver during the frequent lifting of a newborn. It keeps the baby within easy view and reach during sleep times. As the baby grows, the mattress will need to be lowered to accommodate new abilities. For a detailed walkthrough of the adjustment process, see the article on crib mattress height adjustment.

How mattress height positions work

Most full-size and convertible cribs offer three to four mattress height positions. The positions are typically adjusted by moving the mattress support platform to different sets of holes or brackets on the crib frame. The highest position is for newborns, the middle positions for infants who can sit up, and the lowest position for toddlers who can stand.

Adjustment methods vary by crib model. Some cribs use a simple screw-and-bracket system, while others use a spring-loaded mechanism. Always refer to the maker's assembly instructions for the specific steps to change the mattress height. The crib mattress height adjustment article explains the general process.

When to lower the mattress

The mattress should be lowered as the baby reaches new developmental milestones. A common guideline is to lower the mattress when the baby can sit up on their own. At this point, the baby may be able to lean over the crib rail if the mattress is too high. The next lowering is when the baby can pull to stand. The lowest setting is used when the baby can stand unassisted, to make it more difficult to climb out.

The exact timing depends on the individual baby's development. Some cribs have markings or indicators for each height. The maker's instructions often include recommendations for when to adjust the mattress. For safe sleep guidance, refer to the U.S. Consumer Product Safety Commission's Safe Sleep page and the Safe to Sleep campaign. These are authoritative sources for creating a safe sleep environment.

Mattress height in different crib types

Full-size cribs typically offer the most mattress height positions, often four. This gives you the most flexibility as the baby grows. Mini cribs may have two or three positions due to their smaller frame. Convertible cribs that turn into toddler beds or daybeds usually have the same adjustability as standard full-size cribs.

When choosing a crib, check the listing for the number of mattress height positions. Most listings state this detail. If it is not stated, you can ask the seller or the maker. For a comparison of mini and full-size cribs, see mini vs full-size cribs.

What to look for in a crib listing

Look for a crib that clearly states the number of mattress height positions in the listing. A crib with at least three positions gives you flexibility as the baby grows. Some cribs offer four positions, which allows finer adjustment. Also consider the ease of adjustment. Some cribs require tools to change the height, while others have tool-free mechanisms. The maker's instructions will describe the process.

If you are choosing between a convertible and a non-convertible crib, you may also want to review the convertible crib stages to understand how the mattress height fits into the conversion timeline.

Mattress height and crib conversion

Convertible cribs that change into a toddler bed or daybed often retain the same mattress support platform. The mattress height positions are used before conversion. Once the crib is converted to a toddler bed, the mattress is typically placed at the lowest position and the front rail is removed. Some convertible cribs allow the mattress to be used at different heights even after conversion.

For more on conversion stages, see the article on convertible crib stages. Also consider the difference between mini and full-size cribs if you are deciding on the crib size for your nursery.

Adjusting the mattress safely

When you lower the mattress, always follow the maker's instructions included with your crib. The process may involve removing the mattress, unscrewing or repositioning the support platform, and securing it firmly. If you no longer have the manual, you can often find it on the maker's website or by contacting customer service.

After each adjustment, ensure the mattress support is locked in place and the mattress sits flat and level. For guidance on safe sleep surfaces, the CPSC's Safe Sleep page and the Safe to Sleep campaign provide important information. You can access them through the links in the sources section below.

What to pick for your situation

Questions

How many mattress height positions do cribs typically have?

Most full-size cribs offer three or four positions. Mini cribs may have two or three. The number is usually stated in the crib listing. For more on how to change them, see the mattress height adjustment article.

Can I adjust the mattress height myself?

Yes, mattress height adjustment is designed to be done by the caregiver. The maker's instructions provide the steps. Some cribs require a screwdriver or other tool. Always follow the manufacturer's guidance.

What happens if I do not lower the mattress as the baby grows?

If the mattress is too high, a baby who can sit up or stand may be able to lean over the crib rail or climb out. Lowering the mattress keeps the baby contained. Refer to the maker's instructions for height settings.

Do all cribs have adjustable mattress heights?

Most full-size and convertible cribs have adjustable mattress heights. Some portable or folding mini cribs may have a fixed height. Check the listing for details. See the mini vs full-size crib article for comparison.

Is the highest setting safe for a newborn?

The highest setting is standard for newborns. For safe sleep practices, refer to the CPSC's Safe Sleep page and the Safe to Sleep campaign. These are authoritative sources for creating a safe sleep environment.

When should I lower the mattress from the highest setting?

Lower the mattress when the baby can sit up on their own. The next lowering is when the baby can pull to stand. The lowest setting is used when the baby can stand unassisted.

Can I use the highest setting for a toddler?

No, the highest setting is only for newborns and young infants who cannot sit up. Toddlers need the lowest setting to prevent climbing out. Follow the maker's recommendations for height positions.

How do I know the exact height positions for my crib?

The maker's instructions specify the height positions and how to adjust them. If you no longer have the manual, you can often download it from the maker's website or contact customer service.