A new way of looking at environmental variables that may affect the age at menopause

Environmental variables that might affect the age at menopause were analysed by means of the segmentation method AID. Marital status, occupation, smoking habits, age at last pregnancy and height were shown to be significant discriminating variables. The material and design of the study and the method of analysis are given and its results are discussed. A proposal is made concerning the nature of a 'secular trend'.