If you're considering a piece of baby jewellery as a first birthday gift, consider the amount of growth baby will undergo in the next few years. Baby bangles with an extension for growth are a great buy, giving years of wear. Ditto little bracelets with an extension.
Baby necklaces also, can have an extension for growth, or the ability to be clasped at any point along the necklace, is a great asset. Many baby bracelets are able to be closed in this manner.
Sizing isn't a problem with baby brooches, however, most babies stop wearing their brooches by about 18 months which makes brooches less of an option for a first birthday gift.
Baby/children's charms are a great idea for any child's birthday. Give them a naked charm bracelet at age one, and add to it with a new charm at each following birthday. This is a great idea adopted by many grandparents, Godparents and aunties.
Some mothers have their baby's ears pierced at an early age, which also gives the option of baby earrings, of which there are a huge selection, for an inexpensive gift that will never be too small.