you can use safty pillow. That kind of pillow is designed for baby. Inside the pillow, you can found a lots of holes in there in order to prevent baby upside down accidentally.
Yes, the doctor recommend not to use it till one year old. I follow the rules till last month as I found my BB back head (後腦) is very very flat.
Then I use the pillow.
As the newborn baby are unable to 轉身, in my personal comment, it is Ok to use the pillow.
U can buy it at department store under baby section.