Holly:
I'm not aware of any rumors that using a Baby Bjorn can cause damage to the spine of the wearer. However, when you talk to large numbers of mothers who've worn the Bjorn, you will find that most of them stopped using it because it hurt -- if not immediately, then by the time their baby reached a certain size or weight. The "Active" version may be reasonably comfortable for a baby up to 8-12 months, but the regular version is usually too painful to the mom's back or shoulders by 4-6 months, if not before. Honestly, it's hard to recommend the Bjorn when there are so many other adorable, stylish and practical baby carriers that are also very comfortable to wear until your baby reaches toddlerhood and even beyond!

As for other rumors about spinal damage, yes, there are some indications that the baby's spine or hips could be damaged by the baby being held frequently and for long periods of time in a Bjorn, or any other carrier or device that supports baby by the crotch and allows the baby's legs to dangle straight down. There's no real hard evidence to support this idea, but some knowledgeable people have inferred this from the incidence of hip dysplasia in certain populations where this carry position is common, the fact that the legs-dangling position isn't one that babies adopt naturally, and similar factors. Here are a couple of (rather biased) articles on the subject:
http://www.continuum-concept.org/rea...nalStress.html
http://www.storchenwiege.com/babycarrierresearch.htm

Should you and your baby happen to like the Baby Bjorn, I doubt there's too much cause for concern especially if your baby isn't in it 24/7. But as I said, there are so many other wonderful choices of fashionable slings and carriers that if you haven't yet purchased one you love, it's well worth exploring the alternatives!

Colleen:
I would recommend she consult with a physiotherapist or her doctor. If she has been recommended against carrying heavy loads etc., she may wish to heed this recommendation and get the go ahead from her Dr.

As a person with back probs., I always recommend a good 2 shouldered carrier that also carries the weight in the hips and torso: a Wrap being #1.

Also, I am quite small, and do find my 21lbs boy causes me to compensate A LOT by pushing out either my butt or chest depending on my carry.

This is something she may wish to self evaluate on as well, whether simply her own compensation for balance may cause issue.

A carrier that provides a variety of carrying positions maybe a good suit if she does want to wear. One that will allow her to vary up the different muscles, strains etc., so a wrap again.

She can do hip carries, back and front carries.

Marie:
I'm 5'6", about 125lbs. Not quite petite, but fairly small. I, too, have scoliosis, and it's between my shoulder blades. I actually used a snuggli w/ my first child, and it was okay, but became more uncomfortable as she grew. I barely used it w/ my second and third children because of the discomfort, and tried my fourth in it only once before throwing it across the room in pain and annoyance. It hasn't seemed to make the scoliosis worse, but it sure aggravates it.

Finally, I found other baby carriers. I tried a ring sling, but after a few months it bothered my back. I finally got into wraps. Relief! At last I could carry my son in front or on back for hours at a time, and no pain, no discomfort. The cloth going over both shoulders are nice and wide and really distribute the weight across my entire back, using the muscles for support. I also like the asian style baby carriers. The wide straps help distribute the weight across my back and it doesn't focus in one spot on my spine.