Most cribs come with a mattress support that can be set at two or three different heights, and raising it to a higher position is a straightforward adjustment you can make in about 10 minutes. The catch: your baby’s age and physical abilities determine which height settings are safe. A higher mattress position is only appropriate for newborns and young infants who can’t yet sit up or pull themselves to standing.
Why Parents Want a Higher Crib
If you’re searching for this, you’re probably tired of leaning deep into the crib to lay your baby down or pick them up. That’s a real problem. Repeatedly bending over a low crib rail strains your back, shoulders, and core, especially during nighttime wake-ups when you’re exhausted and your form suffers. The good news is that if your baby is young enough, you can raise the mattress support to reduce how far you need to reach.
How to Adjust the Mattress Support Height
The mattress support is the platform inside the crib that the mattress sits on. On most cribs, it’s held in place by bolts that slide into pre-drilled holes or hook onto brackets at different levels on the crib’s interior posts. Here’s how to change it:
- Remove the mattress and bedding. Pull everything out so you can access the support platform and its hardware.
- Unscrew the bolts. Most cribs use four bolts (one at each corner) that attach the support to the crib frame. Keep them somewhere safe.
- Move the support to a higher position. Line it up with the next set of holes or bracket slots closer to the top of the crib.
- Reattach the bolts. Tighten them firmly at the new height.
- Replace the mattress and check stability. Press down firmly on all four corners and the center to make sure nothing shifts or wobbles.
Check your crib’s manual for model-specific instructions. Some cribs use a hook-and-peg system rather than bolts, and the process differs slightly. If you’ve lost the manual, most manufacturers post them online as PDFs.
When a Higher Setting Is Safe
The highest mattress position is designed for newborns and young babies who cannot yet roll over or push up on their hands and knees. Federal safety standards require that the distance from the top of the mattress to the top of the crib rail be at least 26 inches when the support is at its lowest level. At higher settings, that distance shrinks, which is fine for a baby who can’t move much but dangerous for one who can pull up.
Cleveland Clinic pediatrician Dr. Sarah O’Connor recommends lowering to the middle setting before your baby can sit up independently, commando crawl, or get onto hands and knees. That typically happens around 6 months. By the time your baby can pull to standing, usually around 9 months, the mattress needs to be at the absolute lowest position. A baby who can stand in a crib with a high mattress setting can topple over the rail.
If your baby has already hit these milestones, raising the mattress is not a safe option. Skip ahead to the ergonomic tips below instead.
Don’t Add Anything Under the Mattress
Some parents consider placing boards, foam, or other materials beneath the crib mattress to boost its height beyond what the built-in settings allow. This creates serious risks. Any added material can shift, creating an uneven sleeping surface or gaps between the mattress and the crib sides. Federal regulations limit the gap between a full-size crib mattress and the crib walls to no more than 1 3/8 inches. For non-full-size cribs, the limit is even tighter at half an inch. Gaps larger than these measurements pose an entrapment hazard.
Similarly, swapping in a thicker mattress to raise the sleeping surface is problematic. A thicker mattress reduces the effective height of the side rails, meaning your baby is closer to the top and more likely to fall out as they grow. Crib mattresses are designed to specific dimensions for a reason: they need to fit snugly and keep the rail-to-mattress distance within safe limits. Always use the mattress that came with the crib or one that matches the manufacturer’s size specifications exactly.
Replacing Damaged or Missing Hardware
If you can’t adjust the mattress height because bolts, brackets, or support hangers are broken or missing, contact the crib manufacturer for replacement parts. Don’t substitute generic hardware from a hardware store. Crib support systems are engineered to bear a specific weight load at specific attachment points, and mismatched parts can fail. The Consumer Product Safety Commission has issued recalls in the past specifically because of faulty brackets and mattress support hangers that cracked or detached. Using manufacturer-approved replacement kits is the only safe route.
Protecting Your Back With a Low Mattress
Once your baby is mobile enough to require the lowest mattress setting, reaching in and out of the crib gets harder on your body. A few techniques can help. Stand as close to the crib as possible and widen your stance to lower your center of gravity. Hinge at your hips rather than rounding your back, and keep your baby close to your chest for as long as possible as you lower them down. Engage your core as you bend, and try to avoid twisting. Keep your shoulders and hips facing the crib rather than rotating to one side.
Outside the crib, small changes help too. Keep diapers, wipes, and pajamas within arm’s reach of the crib so you’re not carrying your baby across the room repeatedly. When feeding, use pillows to support your position so you’re not hunching over. The goal is to bring your baby up to you rather than folding yourself down to your baby whenever possible.
Cribs With Limited Height Options
Some older or budget cribs offer only two mattress positions instead of three. If your crib’s highest setting still feels too low, you’re limited by the crib’s design, and there’s no safe way to modify it beyond those built-in positions. If back strain is a persistent issue and your baby is still a newborn, a bedside bassinet with an open side that attaches to your bed can eliminate the deep-reach problem entirely for the first few months. Once your baby transitions to the crib, the ergonomic lifting techniques above become your best tool.