"It's not that there are new risk factors; it's that now not all babies are sleeping on their tummies, so other things can be uncovered,"...
Bed-sharing is when infants share a bed with parents or another family member, often common when a child is nursing. Other risk factors tied to SIDS include being male, being exposed to alcohol or cigarettes in the womb or smoking after birth, or overheating caused by thick pajamas or blankets.
"The impetus for bed sharing is usually to make nighttime nursing easier, but there are cribs available that are placed right next to the bed to allow proximity without the risk."
I have 3 children. They all slept with me in my bed on their tummies. This was the only way I could cope. They are all alive and well. I didn't drink alcohol, take medication or smoke. When you have them in the bed with you, then you are able to better monitor their body temperature and are a aware of their movements whilst they sleep.