I manufacture childrens clothing for a couple of designers and have recently develpoed my own childrens line.
Myself and 1 other designer use Winifred Aldrich standard metric body measurements these start at
2 years = chest 54cm waist 53cm
3 years = chest 55cm waist 54cm
4 years = chest 57cm waist 55cm etc. etc.
At 8 years they increase by 3cm increments on the chest but continue to increase by only 1cm on the waist.
Now let me tell you neither of my children ever had these measurements at those ages. My daughter weighed 9lb 3oz at birth and my son born 2 months prem weighed in at 7lb !
They were both the biggest in their class at primary school . My son is now 18 and to put it bluntly is built like a " brick out house !!" He played rugby for the school until he dislocated his knee, my daughter at 25 is 5'2" and 10 stone, she's been that weight and height since she was 11.
Just like adults, kids come all shapes and sizes. If it wasn't for odd shaped people I would never have had 3 alteration shops. The perfect size 12 does not exist !
According to Winifred I should be a size 22 yet I fit into M&S 16 trousers and 18 tops. Body shapes have changed over the years. I used to love dressing up in my mams wedding dress when I was 8, I could just squeeze into the 22" waist dress !!!
Getting back to the business in hand, If your looking for a UK based manufacturer who can design and pattern grade to your requirements then please get in touch I'm sure I could help