The interval between confinements.

Data from New South Wales are analysed to show how the interval between confinements depends on the parity of the mother. When an average interval is calculated it is a weighted average for mothers of varying parity. The weights depend in part on the parity progression ratios and as changes in the parity progression ratios alter the composition of the population by parity, this affects the weightings used and thus affects the average interval obtained.For any interval, age of mother can be calculated at the birth of either child. When age of mother is calculated at the birth of the second child, it is found that the interval is shorter for younger mothers than older mothers. However, when age of mother is calculated at the birth of the first child, there is no significant variation in the interval with age of mother. [ABSTRACT FROM PUBLISHER]