A comment on "Recent European fertility patterns: Fitting curves to 'distorted' distributions" by T. Chandola, D.A. Coleman and R.W. Hiorns.

This article presents a comment on an article which discussed a model of European age-specific fertility patterns using Hadwiger functions. The authors fit the functions to an array of European populations and, in order to interpret the parameters, show the high correlation between a and total fertility, c and mean age of the mother, and ab/c and the modal age specific fertility rate. The authors reflect the analytical relationship between the parameters of the Hadwiger function and the properties of such a function which are developed. As the authors conjectured, c is needed in the analytical mean age of the Hadwiger function, and the analytical total fertility is proportional to a. The analytical total fertility of Hadwiger functions can be obtained by integration over an interval, which requires the c parameter to be positive. In exploring the relationship between the modal age at childbearing and the Hadwiger parameters, the modal age was obtained by differentiating f(x) with respect to x and equaling to zero. The a parameter is just an intensity parameter which should not affect the modal age. The c parameter reflects mean age at childbearing, and that there should be a direct relationship between mean and modal ages.