[mamaMAMAma]

I used the baby byorn with dd#1 early on. I wished I'd read http://continuum-concept.org/reading/spinalStress.html back then, but... Now with dd#2, we've been very happy with the pouch sling and our wrap (newborn cross wrap position). I think the tibetan carrier is very cool and would like to start using that carry. Then I reread the article and thought maybe I should wait a bit longer (until dd#2 can sit up by herself) before using any vertical carries. Dd#2 is 3 months old and about 15lbs. Does the tibetan carry put all the stress on the spine since dd#2's legs would be dangling out. Maybe I'm just confused, in which case please correct me.

 

[EnterGently]

The problem is the narrow crotch area which leaves baby hanging in an unnatural position (and while articles like the one you mentioned above are not based on studies, most professionals agree with the info. and it just makes sense). You can definitely do vertical carries with a newborn from day one, as long as their knees are up or they are not being carried straight hanging from the crotch (with narrow fabric between the legs). Any ring sling or pouch or wrap etc. which allows you do do a T2T carry is perfect. Any carrier with a wider base will allow you to tuck the legs in froggy style, or as baby gets older, leave their legs out in a more sitting position is great.
The Tibetan carry is fine for a newborn cause they are not hanging on their spine. The fabric supports them behind the back and again behind the knees, just like a T2T in a ring sling would.
Sure a cradle carry seems ideal for newborns but some just are not very comfortable that way and prefer to be upright. We carry them like this in our arms and the sling just mimics that.