I would choose a 5-inch mattress which has a waterproof cover. Toddlers like to bounce in their cribs and they will find a 5-inch mattress fun to bounce on. Don’t get a mattress that’s too thick; that may cause baby to bounce out of the crib.
Waterproof Mattress Cover
Although you may already have the waterproof cover that came with the mattress, a separate waterproof mattress cover is essential. Leaks can happen and you won’t want to wash the mattress cover too many times as it may tear. Also choose one which covers the whole mattress and not just the center of the mattress; when mobile, babies roll around and sleep anywhere in the crib.
Fitted Crib Sheet
Babies like to sleep on their bellies so it is important that the sheet is snug and fit against the mattress so baby’s airways will not get blocked. You may want to buy three or more sheets so you will have a clean one handy. Cotton is best.
When babies are mobile, they will hit their head/face against the sides of the crib. Go for the ones that wrap around the rails; they’re pricey, but protect your baby from a bruised head.
The above items are all you actually need to put in the crib. Also, part of creating the perfect crib is knowing what not to put in the crib. Anything that might block the baby’s airways stays out of the crib. To keep it simple, nothing else inside the crib but the baby.
Unnecessary Items in the crib
Stuffed Toys – Although nice to snuggle with, these can block baby’s airways when sleeping. You may want to play with a stuffie in the crib during playtime but by no means leave it in the crib.
Mobile Toys – These are overrated. They don’t really calm the baby or put help them fall asleep. Most babies sleep better when it’s quiet.
Pillows – Frankly babies don’t need pillows. Their heads are large enough that sleeping without a pillow is perfectly comfortable. I do use pillows as bumpers as seen in the image above.
Blankets – I would hold off on giving the baby a blanket for as long as possible because many babies like to cover their faces with blankets. Wearable blankets, however, are safe and keep baby warm.