Ideally, you should to look for a mattress pad that is both soft and firm, as well as extra-absorbent. In case there are any mis-happenings or spit ups, and it is covered in plastic then it might as well be the worst one you could have found.Most of the time, you will be able to find a crib mattress pad made of wool or cotton. These are the standard and they are very comfortable and absorbent, especially cotton. Cotton pads are also much more likely to be anti-allergenic than those made of wool. However, a wool pad is relatively absorbent and their softness provides the perfect temperature for a sleeping baby, which is a huge plus.