Will the BabyBjorn endanger your infant's health?

You don’t have to spend very long on the Internet as a parent to be made to feel that you are essentially abusing your child every 3 seconds. Not feeding them organic. Using formula. Daring to carry them, even just into the house, in a car seat. Using a pacifier. Co-sleeping. Not co-sleeping. The latest thing I came across was the dangers we were imparting on our infant (second, mind you, our first is a healthy 4 year old who went through the same things) by using a BabyBjörn infant carrier. They say it will give your kid hip dysplasia. But will it?

Recently my wife has become involved in “baby wearing”, which has become quite a movement. Like many groups of that nature, various rumors and potential woo have started to circulate. A particular idea that my wife wanted me to look into was whether the BabyBjörn -- and presumably other carriers like it -- can lead to hip dysplasia. If you’re confused about why BabyBjörn would not be proper equipment for “baby wearing”, it should be clarified that in general that movement only uses the fabric “slings”, “wraps” and “soft-structured carriers” (SSCs) and seem to shy away from the front-wearing backpack-like items, frequently calling them “crotch danglers”.

Some History

As expected, most people discussing infant carriers or using the term “crotch danglers” will fail to cite any sort of evidence about their claims. As best I can tell, the term originated in a 1996 article by Chiropractor Rochelle L. Casse, D.C. for The Continuum Concept entitled “Infant Carriers and Spinal Stress“. In my searches trying to track down information, I saw her name referenced a couple of times before finally locating the actual article. Her belief is that the infant carriers, jumpers, walkers, etc of the time (around 15 years ago) would lead to ismthic spondylolisthesis, which is basically slippage of the vertebrae out of place. In the article, Casse makes a prediction that, if true, should be quite easy to verify and would presumably confirm the hypothesis about non-sling infant carriers:

If the trend continues in the U.S. to carry infants in carriers (or place them in walkers, jumpers, etc.) that place their spines in a weight bearing position before the spine is developmentally ready to do so, I believe we will see an increase in the incidence of spondylolisthesis.

She cites 5% as the rate at the time of writing, though I don’t know if the figure was updated when she edited for the website. According to Wikipedia the current prevalence is 5-7%, so there certainly does not appear to have been a drastic rise from the data I can locate.

Note that at no time does even she mention hip dysplasia. The references I could find on spondylolisthesis do not cite infant carriers as a potential cause. In the article, Casse mentions that most people believe it is genetic but that she sees it as environmental, especially in reference to Eskimos who apparently have a high rate. However, she does not cite any evidence except her own views.

Hip Dysplasia... or poor spinal development?

So the first potential myth to look into is whether BabyBjörn and it like can lead to hip dysplasia. I had of course never heard of this, happily carrying our first daughter (now four) on many a trip to the grocery store and through malls. But is there any truth to this idea?

My wife sent me a link to one of the community sites making the claim. In there, multiple posters say to check a particular blog article, as well as including links in the forum posts to other blog articles which, supposedly, explain why “crotch danglers” are so bad. Clicking on the links (even the one that supposedly has so much “good information”) ends up providing no information about actual dangers. They appeal to emotion: “Would you want to be carried around by your crotch?” or “Well, there’s no back support for you”. Instead they just recommend all the carriers and slings that you should be using. The one link I found to what seemed to be much less alarmist and more balanced was actually the manufacturer of a competing product to BabyBjörn, Boba (makes what is referred to as an SSC, soft structured carrier).

That article actually discusses products (unnamed, but pictured) in terms of poor spinal development when front-facing. The product they picture which looks like the “Björn” they appear to have no beef with when the baby is placed facing the parent:

The wider base of the above carrier would provide some spinal support (maintaining the natural convex “c-shape”) if the baby was turned facing the father and his bottom was seated in it”

otherwise they say it causes the baby’s back to curve “unnaturally” (concave).

(Improper) swaddling the real danger

That article does not discuss hip dysplasia until they move on to swaddling (which we also do with our infant). The author even references studies! It’s not the swaddling per se, but swaddling when the legs are held tightly together rather than letting them spread, especially when there is congential dysplasia. For me personally, my daughter ends up with loose legs because it’s nearly impossible to get a tight swaddle. So, assuming the author is right, my own inadequacy in this turns out to be safer. The systematic review (yay!) by Van Sleuwen published in the American Association of Pediactrics (AAP) journal seems to be positive in support of swaddling except noting the possibility of hip dysplasia if done too tightly, and also a danger of SIDs once the infant is trying to turn over (I was already aware that once your infant can turn over swaddling should be discontinued). Support-wise (from the review),

Eleven epidemiologic studies have shown that the incidence of DDH (developmental dysplasia of the hips) is highly correlated with the traditional use of swaddling for newborn infants. (Van Sleuwen)

And,

This detrimental effect of swaddling is related to the misapplied use of the practice. Swaddling in a manner that allows the hips and knees to move freely might not have this risk-increasing adverse effect, but more studies are needed to test this hypothesis. The studies that showed beneficial effects of swaddling have been conducted with the infants' lower extremities wrapped loosely, but the contribution of wrapping their legs on sleep, pain relief, and excessive crying also needs to be addressed. (Van Sleuwen)

PubMed currently has 11 results (reviews and individual studies) for “hip dysplasia swaddling”, but none that I could find related to carriers.

Responses to claims of hip dysplasia from BabyBjörn

So if you are confused... we started on BabyBjörn (and similar carriers) but have made it all the way to swaddling. Such is the path of rumors. But back to carriers (emphasis mine):

Although different in appearance, any modern baby carrier that does not support an infant’s legs (in a flexed abducted position oriented toward the wearer), any front facing carrier with leg holes is no more developmentally sound than a papoose (Boba)

What does BabyBjörn have to say on the matter? Naturally, the official response from BabyBjörn is a resounding no:

Your child cannot develop hip dysplasia or hip luxation by being carried in a baby carrier. Hip dysplasia, or hip luxation, is a congenital condition diagnosed through a medical examination. The notion that baby carriers can cause hip dysplasia is a misunderstanding and has no scientific foundation. This is confirmed by leading child orthopedists.

But it is perhaps reasonable to look further than the manufacturer of a product that is the target of the claim. Their answer references “leading child orthopedists”. It looks like they are specifically referring to Dr. Amanda Weiss Kelly and Dr. Allison Gilmore, which they feature in an article and video saying that the BabyBjörn “holds babies’ hips in the optimal position -- the abducted position”. But we’re still within the realm of the actual BabyBjörn site.

Perhaps we can see what other experts have to say.

While hip dysplasia might be present at birth (congenital, CHD) it is usually detected later on during development of the child (developmental, DDH).

The International Hip Dysplasia Institute has a page on the causes of Hip Dysplasia.

• Babies in the breech position are much more likely to develop dysplasia

• Girls are 4-5 times more likely to to have hip dysplasia than boys

• Cultures using cradleboards and papooses have high rates of hip dysplasia (see discussion above on very tight swaddling)

They also have a page discussing baby carriers specifically:
To start with, “The Medical Advisory Board of the IHDI does not endorse nor advise against any particular baby carrier or other equipment”. They do not say, “Run, do not walk, away from BabyBjörn!”. They then have some pictures demonstrating proper positioning, similar to what was shown on the site above from Boba and others. Essentially the baby should be worn facing the mother with the thighs well supported.

In the case of slings, similar rules apply: don’t place the baby in so that their legs are forced together (picture holding them horizontally across your body where their legs end up together).

All of their examples end up being with the baby facing the parent, which despite the community forums, seems to be actually well-evidenced to be safe (or at least there does not seem to be anybody credible citing evidence against it).

So is front-facing the problem?

BabyBjörn has a section of their site devoted to answering questions about front-facing, which I urge the reader to take a look at. In it they have articles from pediatricians, professors and other doctors discussing the BabyBjörn. They were most likely paid for their recommendation, so keep that in mind. But they are bringing to bear much more than those making the alternative claim.

I decided to do something insane and actually read the directions for the BabyBjörn that I own. I of course haven’t got a clue where the paper copy is, so I had to use the online version. The directions specifically note that the child should be well-supported by the bottom and the product must be adjusted based on their height. Odds are, most people never do that. If you make the correct adjustment you can see from the picture that the baby’s legs end up spread out, and certainly not simply “dangling by the crotch”. Additionally, the “Björn” we have is rated up to about 26 pounds. If you try to put a 40 pound 3 year old in there, they are certainly going to be straining the fabric a bit. I actually took pictures of me holding my infant in our carrier, with the adjustment placed in various positions. As far as I can tell, her legs are abducted and the thighs have partial support. But her feet are not supported, which is one of the recommendations. But I definitely would not classify her as “dangling” from the crotch. Also one interesting thing I’ve found myself instinctually doing is putting my hands on the bottom of her feet to hold them up while walking.

So I am on the fence a bit about front-carrying. My daughter seems to enjoy it and it certainly does not place her legs straight down, her hips are in fact supported, just not as close to the knees as perhaps is recommended. Until there is actually a study, or preferably multiple, linking front-facing carriers to actual, rather than what I would call hypothetical but-doesn’t-that-look-really-uncomfortable “common sense” evidence, I will continue to carry my baby occasionally front-facing, but certainly with more awareness.

Conclusion

Despite this starting as an intent to look into BabyBjörn (and carriers like it), there appears to be much more risk from incorrect swaddling. The closest thing I can find to an actual counter-indication is for front-facing, but as best I can tell the evidence for this is circumstantial/anecdotal, especially if the carrier is placed at the proper adjustment following the manufacturers instructions. Babies will tend to be swaddled for much longer stretches of time (8-10 hours a night) than they will be placed in a carrier. I will certainly be more careful about my swaddling techniques (perhaps continuing how I do it any how, but more conscious of it) and will make sure to properly read the safety guidelines for any product meant for young children.

If anybody is able to locate evidence (probably some epidemiological study) of an actual correlation between a front-facing carry and spinal or hip issues, I would definitely be interested in it. What I really came across in researching this was simply a lack of evidence, which does not disprove that front-facing infant carriers, such as the BabyBjörn,  can lead to spinal and hip issues. But neither does a lack of evidence support the idea of just "waiting and seeing" when anecdotally, the problems do not manifest (and neither my children nor apparently millions of others). 


UPDATE 7/1/2013: The manufacturer of BabyBjorn now has a site that is essentially their response to the claims against the product. While obviously not "independent", it's probably worth a look for those who have concerns.

REFERENCES
Boba. “strollers, baby carriers and infant stress”. Published 2010. Visited January 21, 2013. <http://www.bobafamily.com/research/strollers-baby-carriers-and-infant-stress/#2>
Van Sleuwen, Bregje E., Adèle C. Engelberts, Magda M. Boere-Boonekamp, Wietse Kuis, Tom WJ Schulpen, and Monique P. L'Hoir. "Swaddling: a systematic review." Pediatrics 120, no. 4 (2007): e1097-e1106.
BabyBjörn. “Q&A: Baby Carriers”. <http://www.babybjorn.com/customer-service/faq/baby-carriers/>
International Hip Dysplasia Institute. “Causes of Infant Hip Dysplasia”. <http://www.hipdysplasia.org/developmental-dysplasia-of-the-hip/causes-of-ddh/>
International Hip Dysplasia Institute. “Hip Health in Baby Carriers”. <http://www.hipdysplasia.org/developmental-dysplasia-of-the-hip/prevention/baby-carriers-seats-and-other-equipment/>