My midwife strongly advised against the ones you wrap yourself for 2 reasons:
1. The baby can slip out
2. Its not good for your body to carry the baby on the side etc because you put uneven pressure on your back/ pelvis etc.
I have the baby bjorn, the cheapest one they had I think, it seems great and looks good too.
Your midwife needs to do a bit of research on proper slings because a properly used wrap will not endanger the baby and newborns are meant to be in the froggy position facing your chest. When they are older, yes, a kangaroo carry to one hip using a ring sling can be uncomfortable but that's when you want to switch them to a back carry anyways.
A Baby Bjorn puts the pressure on the baby's crotch and when facing forward, allows their necks to slump forward (which is why forward facing is not recommended). The weight limit is very low for the price of the sling and can't be used on your back, so most women stop babywearing at 4 months with a Bjorn when really that's one of the best times to get started (at 6+ months, the back carry makes life very simple).
Bottom line... proper informed babywearing is very safe and does not cause problems to mother's body. It also makes her life easier. Many laymen are generally misinformed as to what a proper sling/wrap is, and people give out all sorts of information. I've been wearing my son since the day he came home from the hospital and I still wear him on my back at 1, I've never used a stroller.
Babywearing is a cornerstone of attachment parenting and makes life easier for mom, plus encourages bonding (especially useful for myself who was unable to BF due to my LO's birth injury) and many moms/cultures swear that it reduces crying/"colic" [4th trimester theory].
I own a Baby Bjorn Active (bought in pregnancy), Infantino bag sling (not recommended at all, considered quite dangerous actually), an Ergo (highly recommend, used daily), a Moby Wrap (great for newborns) and a hotsling (one shouldered, not too comfy, used sparingly for kangaroo carry). I don't recommend the Bjorn or Infantino. Infantino bag sling is unsafe, and the Baby Bjorn has so many negatives for the price, I really think people can get a much better/long term/useful/comfy sling for the same price.
Sorry to rant on, I just really love babywearing and wish more correct information was presented!