On estimating fertility using first and second order births

"An attempt has been made to present two regression equations for estimating total fertility rate from the birth order data. While one of the equations has been derived from the longitudinal data of Malaysia another has been obtained from cross sectional data on Mother's total fertility rate...and births of orders one and two. These equations are used to estimate the [total fertility rate] for the districts of [Uttar Pradesh, India,] which are quite close to the estimates obtained by using other methods."