There is no definitive answer to this question as it depends on a number of factors. If you are using a wedge to prop up your baby's head in order to prevent reflux, then it is generally considered safe. However, you should always check with your pediatrician first and make sure that the wedge is the appropriate size for your bassinet. Additionally, you should never use a pillow or other soft object in place of a wedge as this can create a suffocation hazard. If you are using a wedge for any other reason, such as to increase the incline of the bassinet, then you should exercise caution and consult with your pediatrician first.