The Ergo Baby Carrier's ergonomic design supports a correct sitting position for the baby's hip, pelvis, and spine growth. It disperses most of the baby's weight between the hips and thighs, which helps to eliminate compression of the spine when hanging by the crotch, as in other commercial carriers. The Ergo also balances the baby's weight to parents' hips and shoulders, making it healthier for the parent than wearing a baby sling. It will help keep your body aligned and alleviate back pain so you can carry your baby longer. You'll be amazed how light your baby feels! Parents say they have never felt so comfortable carrying their babies, who are safely attached to their body. It can be worn on the front or back or on the hip. Recommended use from birth (with infant insert) to 40 lbs.