Lower the crib mattress to the next setting as soon as your baby can sit up without help, usually around 4 to 6 months, then drop it to the lowest setting once they start pulling to stand, around 8 to 9 months.
Crib Mattresses
When to move crib mattress down?
A crib mattress sits highest for newborns so parents can lift them out easily. Once a baby sits, rolls, or grips the rail, that height becomes a climbing and tipping hazard. The crib mattress should always sit low enough that the top rail stands well above the baby's chest.
- Most cribs offer 3 to 4 mattress support positions, from the highest newborn setting to the lowest toddler setting.
- Common developmental triggers for lowering a crib mattress: sitting unassisted (about 4 to 6 months) and pulling to stand (about 8 to 9 months).
- A standard crib mattress should fit snugly against the crib frame, with no gap wide enough to trap a baby's limbs.
- Foam crib mattresses sold with CertiPUR-US certification are independently tested for VOC emissions capped at 0.5 ppm.