Aspects of the decline of fertility in Scotland. variables Coale Indices of Fertility and Nuptiality (If, Ig, Ih, Im) as indicators of demographic transition. Economic and social history of Scotland. Measurement scales A.J.Coale `Factors associated with the development of low fertility : An historical summary' in United Nations World Population Conference, Belgrade , 1965 (New York: United Nations, 1965) Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.