Uncertainties in designation of age at menarche in the nineteenth century: revised mean for Denmark, 1835

The earliest Danish study of mean age at menarche by Ravn (Fenger 1850) is analysed with special reference to age recordings and their subsequent groupings into age-classes. Uncertainties of interpretation of the age designations are discussed, and it is argued that, in all probability, mean age at menarche was 17 years in the samples of Danish women born around 1820, rather than below 16 years as believed previously.