The Finnish sauna is a substantial part of Finnish culture. There are five million inhabitants and over three million saunas in Finland – an average of one per household. For Finnish people the sauna is a place to relax with friends and family, and a place for physical and mental relaxation as well. Finns think of saunas not as a luxury, but as a necessity. Before the rise of public health care and nursery facilities, almost all Finnish mothers gave birth in saunas.

Source: https://en.wikipedia.org/wiki/Finnish_sauna