When an infant is in a "reclined" position it places their chin to their chest. Due to the proportional difference of their head size to the body, this crimps their trachea leading to slow asphyxiation. Think of parking a car on a running garden hose.
This is not a new thing, it is just something they no longer label as SIDS because we KNOW it can be prevented. It sometimes falls under the category of SUID, but I hope that stops as it really has nothing to do with it.
It is explained and preventable, YKWIM? The number one airway obstruction, and cause of death in infants, is their own tongue (I am a Pediatric Advanced Life Support Instructor and that is a test question
.)
check out
www.firstcandle.org/
www.heart.org for infant cpr