Eliza was 7lb7oz and she was on 0000 for at least a month, longer in some brands. Then into the 000 which lasted a while. She was only in 0 when she was 1, size 1 when she was 2 etc etc. She is 31/2 now and just starting in to 3's. It depends on their height so much. She is actually a Size 3 height and a size 1 waist - consequently no pants fit her