Parity progression ratios

A parity progression ratios is a measure commonly used in demography to study fertility. The PPR is simply the proportion of women with a certain number of children who go on to have another child.
Calculating the PPR, also known as, can be achieved by using the following formula:
In more developed countries where two-child families are seen as the norm is of critical importance in determining overall fertility levels.
is simply the proportion of women who become mothers.