Ok, I can only judge the sizes in the UK and Brazil. And maybe India and Australia.
I took all Laura’s summer clothes to Brazil as it would be the last opportunity to wear them. Today I decided to have a look at her existing clothes – in theory too big for her as they are mostly 6 months+. To my surprise, Laura outgrew several pieces, mostly the ones from Romania, and fits most of the new big clothes from Brazil. The clothes from India (age 1 year+) are small, and the ones from Australia (6months+) are too big.
I’ll test the American ones soon.