Hi Rachel, my son is in the large but he is 15kgs... They are a very easy fit for him. I find them great to use. I reckon they are definitely better than the nappies you fold yourself but then again if your bubs isn't here yet, then some of the others recommend using flats and covers for the first few months once he/she is.

Pop into the cloth nappy chatter thread, you can find more great info there.