Hi Leah, Thank you for your enquiry. The Lillebaby Complete Original Carrier adjusts to perfectly fit baby at every stage and enables carrying through the “baby wearing gap.” No extra insert should be required. However, we would recommend contacting your nearest Baby On The Move store to clarify your childs size and weight to ensure that this product is suitable for your little one. If you follow the link https://www.babyonthemove.co.nz/store-locations/ this will take you to our on-line store finder. Here you can find contact details for your nearest Baby On The Move store where one of our team experts can help find a suitable solution for a product you may be searching for and assist you with any further questions you may have regarding our range of products available. We hope this has helped with your query.