I wouldn't put a baby in jeans, but I think jeans are fine for toddlers. I think that jeans can be uncomfortable and restricting, so if buying for a baby, I like to buy the soft 'denim' ones. Sometimes I like dressing babies in 'baby' clothes, and sometimes I like dressing them in 'adult style clothes'. It's amazing the difference clothes can make to their appearance.
On toddlers I like them, but only if it's a cold day. The denim gets very hot which would be uncomfortable for them. It looks cute to me on little babies, but I haven't really put jeans on my kids because it looks too hot for them. That and my oldest son got a pair given to him as a really little baby and they were ridiculously difficult to get on over a nappy.
I put jeans on my toddler, since they're fairly practical once your child is walking as they are durable, help prevent grazed knees and don't show dirt too much. On babies who are doing a lot of lying around I would think they would be a bit uncomfortable. I know I don't like to sleep in jeans. Also, I think onesies are cute and practical for babies.
That kind of fabric is not nice for a baby,their skin is very delicate, and also needs to breath.
For toddlers, only cotton type jeans, not the real denim.It gets way too hot when they are playing, plus it has little movement.
Not a big believer in fashion trends for babies,they need to be taken into account.
They are not toys to be dressed up, to look cute or cool.
NO! I love looking at babies wearing baby cloths. They grew p hick enough as it is! My eldest grand-daughter is near 6, & has never worn jeans, hardly any slacks nor anything pink. My daughter has a knack of dressing her in dresses, & leggings, that go so well together in colour & patterns.