Can a blanket over a newborn's face kill them or cause brain damage? or is the risk just strangulation?

Suffocation: About 100 infants die every year in the US after suffocating under/in blankets, soft bedding, wedged into baby bumpers or overlain by parents who sleep with them. How you choose to classify this is irrelevant. Infants under a year of age should be places in a onesie and left in a crib alone with no blanket. When they are old enough to move about/stand/cast off bedding easily it can be used.