AIBU to expect baby clothes to be the same size regardless of where they are bought?

[honeytea]

Inspired by the vanity sizing thread.

I have noticed that baby clothing sizes is very random. The highstreet shops seem to manage to make their clothes pretty uniform when it comes to sizes but the more expensive brands seem to just imagine how big a 2 month old baby will be and make the clothes to fit this random size.

My DS is 2 months old and huge so I don't expect him to fit into clothes made for 2 month old babies but I do expect the size to be consistant. Most of his clothes come from ASDA, NEXT, H+M, primark, and highstreet Swedish shops, he is in age 3-6 months in these clothes without exception. He has a few posh clothes that were given to us as gifts and the sizes are so strange. Today he is wearing a polarn o pyret in size 56 (newborn-1 month) and a petit bateau babygrow in size 6 months.

AIBU to think that it would be easy enough to have a standard size and for shops to make clothes that fit those sizes?

my DD is 3 and on 25th centile she has 1 cardigan that still fits in 12-18months she wears 18-24 month trousers mostly as otherwise too long they are still too big in waist but then she is wearing pants not nappies like most 18-24 months do, despite being shorter than average she has 2 dresses in size 4-5 and they are only knee length, she nursery uniform is age 304 as do not make smaller the skirts are still too big even with adjustable elastic on about 7th hole

its just like adult stuff size 14 in one shop is not the same as 14 in another and 1 pair of 14 trousers may fit well and another in same shop may not as a different cut allowing for different hip/waist ratios I think most stuff needs to be tried on

Nobody is saying babies should be the same size at the same time they are saying if you buy two items of clothing from the same shop in the same size they should be roughly the same size.

All this 0-3, 3-6, etc. sizing is an unnecessary complication. Why not do what other Europeans do and buy for height / length rather than age? That would be much simpler. If you look at M&S - their 18-24 is different by 2 cm compared with other brands' 18-24....