Cadillac 2007 STS Owner's Manual page 41

Every time infants and young children ride in
vehicles, they should have the protection provided
by appropriate restraints. Young children should
not use the vehicle's adult safety belts alone,
unless there is no other choice. Instead, they need
to use a child restraint.
CAUTION:
{
People should never hold a baby in their
arms while riding in a vehicle. A baby
does not weigh much — until a crash.
During a crash a baby will become so
heavy it is not possible to hold it. For
example, in a crash at only 25 mph
(40 km/h), a 12 lb (5.5 kg) baby will
suddenly become a 240 lb (110 kg) force
on a person's arms. A baby should be
secured in an appropriate restraint.
41