2. CARRIERS THAT HAVE YOUR BABY HANGING BY HIS CROTCH MAY BE UNHEALTHY. I had heard that jumpy seats and walkers can be bad for babies' developing bodies, but now there are claims that certain carriers can cause spinal stress. A friend of mine told me about this concern and once I started reading about it, it made sense to me. Apparently the main concern is using a carrier which has your baby dangling by his crotch, e.g. in many of the front infant carriers and even some back framed carriers. Apparently this position can put stress on the spine affecting the development of the spinal curse and possibly spondylolisthesis (slippage of the vertebra). Most of the ones that allow the baby to face forward in front, e.g. the Baby Bjorn, have them dangling this way. Even though this doesn't seem to be a widespread concern yet, it does make sense to me that this position is not a natural position for a baby to be held in. And that's why I like that The ERGO Baby Carrier positions newborns in a sling-like position, until they are able to control their own heads, then in a natural seated position.
https://www.backpainreliefonline.com/babycarriersandslings.html