I've heard that the Baby Bjorn carrier is terrible for the baby's hips and spine, and in doing research came across a whole plethora of devices that can lead to hip dysplaysia. Hip what now?? Actually, I'd heard that term before. It's quite common in some breeds of dogs. I knew that, strangely, but I didn't really know what it is. Here's the explanation from HipDysplasia.org: "If the hips are forced into a stretched-out position too early, the ball is at risk of permanently deforming the edges of the cup shaped socket (hip dysplasia) or gradually slipping out of the socket altogether (hip dislocation). Hip dysplasia or dislocation in babies is not painful so this may go undetected until walking age and may also result in painful arthritis during adulthood." Yikes!! No i understand why the doc gently rotate Kenzo's legs around at his check-up each month, they're looking for signs of this!
Basically, in any activity or situation you should avoid having baby's legs stretched out straight and pushed together. In a carrier, have baby in froggy position or hug position, with legs supported throughout the butt all the way to the knee, with knees parallel to or slightly above butt level. Don't put baby in a jumper, walker, exersaucer, etc for extended periods of time as these put stress on baby's hips. In a carseat or bouncer, make sure baby's legs and hips are free to spread out and bend. When swaddling, have the legs bent up (think fetal position) or use a sleep sack where the hips and legs are loose (go here for a swaddling how-to video). Interestingly enough, because of the danger of incorrect swaddling, it has recently been banned from day care centers, which I think is crazy town because little babies NEED to be swaddled to sleep well! But we all know how the government loves to get involved by telling us what we can and can't do... Anyway, here is some more info & photos showing the good and bad positioning in car seats, carriers, etc.
Some general safety tips for baby wearing:
* As mentioned above, baby's position is key to avoid developmental problems with the hips and spine. Ideally, baby should be in the froggy or hug position, depending on age with legs coming out into hug position after 4 months or so.
* Baby's chin should never be touching his or her neck - this would make breathing quite difficult. Unfortunately, this position is tough to avoid with a newborn in the cocoon kind of slings. Not impossible, but you have to be really careful. I should add laying in the cocoon sling is not great for baby's hips.
* Do not let fabric cover the baby's face. This could cause the baby to "rebreathe" air, which is believed to be one of the causes of SIDS. You not only have to be careful about the sling or wrap's fabric, but also your clothing. When wearing my baby, I sometimes look down to find him face down on my chest after he's passed out, and I have to be careful to make sure his head is turned so that his nose is not nuzzled in my shirt. Or I arrange his hands so they're tucked under his chest to push his head back away from my chest a bit.
Not to rag on Baby Bjorn, but it's sub par for many reasons: 1) bad for hips (as discussed above), 2) bad for spine (doesn't support natural curvature of baby's spine), 3) bad for brain (front facing, baby has no escape from overstimulation). Yet, somehow Baby Bjorn is the most popular and most well known brand of baby carrier in the States. Go figure. Well done to their marketing team >_<
* Read in detail about Hip Dysplaysia, a risk especially in the first few months from bad positioning in car seats, baby carriers, and swaddles.
* Safety tips from Baby Wearing International
* 9 reasons why carrying your baby front-facing is bad