I began to wear this ergobaby carrier since my baby was 8 lbs. From that time on, there was always a unforgetable pain on my back or shouders, although I tried to adjust different positions. I had a strong desire to stop using it within few months. Then I tried to wear it through front position or back position. I feel uncomfortable while I had to wear it within 2 days for my baby who is around a 18 lb. In case that you gain a very stable upper body and core, you have more access to use ergobaby. However, there is no possibility that majority of mothers owns them.So that is why I refused to take advantage of it. In addition, my husband's back also hurts when he had a good try of it one day.