Trainer bras, also known as training bras are esigned for girls who have begun to develop breasts but have yet to be considered "developed" enough to allow for a standard-sized bra to fit properly. They are of simple construction and offer little, if any, support. Training bras were invented in the 1950s, in response to the desire of adolescent and pre-adolescent girls to "fit in" among their more developed peers. However, heavy marketing probably contributed to some of the demand.