Flossie - the ERGO is not recommended for under 4 months due to the leg position. Oscar is nearly 5 months and he is just ready for it - a couple of weeks ago it wouldn't have suited him at all. The newborn insert should be used before then, which is why I used the HAB and the old style Baby Bjorn until then. I still use the BB to face him forward. The ERGO will be fantastic for when he gets bigger and I can carry him on my hip and back too which I can't do with the BB.