Historically, the provision of child-care has been justified as a means of solving pressing social and economic problems of particular groups (of particular families or particular needs of industry). For example, to rescue children from squalor; to provide a workforce in wartime; to enable welfare or low income families to be self-supporting; to retain special skills in the workforce (e.g. nurses, teachers, university staff). Thus, child-care has been provided in a piecemeal way as expediency.