In another worrying report on possible infant deaths caused by the use of sling, "Infant Deaths Prompt CPSC Warning About Sling Carriers for Babies", it is noted that infants of the following condition are discouraged from the use of slings in their early months of life (4 months and below):
- baby in fragile health condition
I would say that even with babies who are born healthily and with normal birth weight etc, infant babywearing has to be handled with care. It is ALWAYS important to look for signs of changes (in skin colour etc.) and discomfort (baby squirming and trying to get out etc.) and do trust your instincts if you feel baby is not comfortable or unsafe.
Have a read at the above article. It is not meant to scare you off babywearing but more like a safety precaution for all of us who need to wear our babies at that young age.