GMC 2003 Sierra - Manual (Page 44)

Newborn fnfarrts need complete support,
including support for the head and neck. This
is necessary because a newborn infant's neck
is weak anct its head weighs so much
compared with the rest of its body, in s crash,
an infant in a rear-facing seat settles into the
restraint, so the crash torces can be
distributed across the strongest part of an
infant's body, the bach and shoulders. Inlants
always should be secur&d in appropriate intent
restraints.
A CAUTION:
The body structure of a young cfrifd is quite
unlihe that of an adult or older child, tor whom
the safety belts are designed. A young child's
hip bones are stilt
SO smal! that the vehicle's
regular safety belt may riot remain lew on the
hJp boneSri as it should, Instead, it may Settle
up around the
child's abdomen. In a crash, the
belt would apply force on a body area that's
unprotectEKt by any bony
Structure. This alone
could oeusE serious or fatal injuries. Young
children always should be secured in
appropriate child restraints.
1-37