Select the highest level when your baby is under 5 months - it is very likely this is the safest choice at the highest setting. Your baby at this stage is, for the most part, immobile and not likely to do any climbing. What we found is that the higher crib mattress level will make lifting your baby easier placing less stress on our backs to frequently place the baby and pick them up. Additionally - it will make it easier to place your hand below the baby’s neck to ensure that you’re providing the most support for their head.
It is recommended to lower the crib mattress level in the middle height as soon as the baby can sit up by themselves and be more mobile on their hands and knees. Now, the exact time your child is able to sit up unassisted varies from baby to baby - but you can expect them to do this when they're 6 to 8 months old (sometimes a bit earlier).
The idea is that as soon as they’re able to sit up, place their hands and knees on the ground, and roll about - it is time to lower the mattress.
One thing to keep in mind that your baby will soon start to stand with assistance - this can be scary in the middle crib mattress setting as they might very well be able to reach the top of the side rail! You might want to adjust the baby's crib mattress levels further.
Cribs that have an additional middle setting (they have 4 adjustable positions) for the crib mattress gives you a little wiggle room to adjust as your baby develops between laying down and being on their hands and knees. We recommend erring on the side of caution, however, and move to the lowest setting as soon as they can stand assistance.
Use this crib mattress support level as soon as they’re able to stand with assistance or pull themselves to a standing position. This can happen between 8 - 12 months. The lowest level will ensure the 26 inch requirement to reduce the chance of injury.
When to Transition to a Toddler Bed?
It is recommended that once your baby reaches around 35 inches in height- you should make the transition to a toddler bed. This does mean you can also change the mattress, as the regular baby mattress might be a bit too firm for your toddler to sleep in. Thankfully, most modern cribs are designed to convert into a toddler bed as your baby grows.