Babyandinfantcan be used before a noun to refer to things for babies or infants.
I'm busy knitting baby clothes for my new granddaughter.
Infant formula can be given to babies from birth until 12 months.
Some words that describe children are disapproving when applied to adults. One of these words isinfantile. It is used to describe something, such as behaviour or humour, that is immature.
The film was full of crass and infantile humour.