Unfortunately, due to your baby’s relative lack of physical stability in the first few months, it’s important to wait a bit before using the back-carrier. However, this doesn't mean that they can't be great tools down the road, making your mobile life much easier.
While your baby can be placed in a front carrier basically right after birth, you should wait to place her in a backpack until she can sit up and support her head on her own, usually around five to six months. Newborns especially crave closeness and contact, and carriers can provide a convenient, hands-free alternative to strollers.
Most backpacks are built around a lightweight aluminum frame that distributes your baby’s weight equally across your shoulders and hips, with a seat and plenty of other features as well. For convenience and savings, search for an adjustable carrier that can switch easily from front to back. Make sure to test the pack for fit and comfort, as carrying your baby on your back for extended periods can get painful. Always check straps, buckles, and ties regularly for your baby’s safety.
Before purchasing a pack, ensure it has a sturdy restraint system — for example, a five-point harness with waist belts, shoulder straps, and a crotch strap. Examine the leg openings to make sure that your baby cannot slip through. Try the pack on with your baby inside before you buy, if you can, so you know that both you and she are comfortable with it. Most models also come with support stands so that your baby can be easily placed inside, and should also include adjustable seats, a removable canopy, and a detachable plastic rain cover. And of course, make sure the pack is easy to clean and wipe down for any unexpected accidents.