I don’t like the Baby Bjorn. (I can just hear the cries of all the Bjorn-wearing mothers across the country: “WHAT? How dare you scorn my Bjorn!”) Here’s why:
Hip dysplasia is simply the abnormal formation of the hip joint. The hip joint is a ball and socket joint (remember that from your 8th grade health class?), which means the ball of the femur (thigh bone) is held into the hip by a soft tissue capsule and many very strong ligaments. When babies are born both the bones and ligaments have not completely developed – this is an advantage for babies as they have increased flexibility to pass through the birth canal. In the first few months after birth the structures that make up the hip joint form rapidly, giving the joint strength and stability.
Have you ever noticed that a newborn has their hips in a frog-legged position? Usually their knees tuck up against their chest with the hips externally rotated (outward facing). This position is beneficial to the hip joint, allowing the structures of the joint to line up properly as all the tissues strengthen and develop.
The way infants are positioned in the womb and in the first few months of life determine whether the hip can form properly. It has long been known that breech positioned babies are more prone to hip dysplasia. Similarly, babies whose legs are forced straight either by swaddling or dangling also have an increased risk of hip dysplasia. Straightening the legs places a lever-like force on the femur, encouraging the hip to pop out of the socket.
Signs of hip dysplasia
The first signs of hip dysplasia are clicking or popping of the hip joint, followed by sway back and/or limitation in range of motion of the joint. Typically pain does not occur for many years, often beginning in adolescence and persisting and worsening as the person ages. Hip dysplasia leads to degeneration of the joint, which can be incredibly painful and crippling.
So why not the Baby Bjorn carrier?
Simply put, the carrier makes the legs dangle, putting excessive force on the hip joint.
Of course, it doesn’t mean that ALL children in the Baby Bjorn will develop hip dysplasia, it means that it greatly increases the risk. (That whole argument “Well my baby was in the Baby Bjorn all day and he’s fine” isn’t a good reason to keep wearing it. It only means that single child wasn’t susceptible or wasn’t in it long enough to develop hip dysplasia.)
There are many excellent carriers other than the Bjorn which are safe, sturdy, and (many claim) way more comfortable anyways. You should note that other carriers that look like the Bjorn (like the Infanto) are just as unsafe, so skip those. Some other great options are the Ergo, Moby, Beco, Boba, and woven wraps like Didymos, Dolcino and Girasol. Check out The Baby Wearer (www.thebabywearer.com) for product reviews. The carrier should hold the legs outward, with support on the entire length of the thigh all the way to the knee joint.
Here are some excellent illustrations by the International Hip Dysplasia Institute that show very clearly what type of carriers are best:
For more information check out The International Hip Dysplasia Institute.