Yes, pacifier nipples and shields vary in size, hardness and shape. The age guidelines take into account the size and hardness of the nipples and shields. For example a 0–2 month pacifier used by an older baby could cause the shield to be taken into the mouth. In case of this event do not panic, it cannot be swallowed and is designed to cope with such an event. Remove from the mouth with care, as gently as possible.