Victoria, Queensland and Tasmania don't collect information on how many previous babies the mother has had, only how many the father has had (including those in earlier relationships).
Guest blogger Peter Martin takes a look into birth statistics and what they tell us about the baby bonus.
They're fair questions. How many babies born last year were first children? And how many were second or later children? We went after the answer with Thursday's release of the ABS births numbers because it would have given us a handle on the number of births who would get the lower $3000 baby bonus announced in the mini-budget for later children instead of the previous $5000.
The ABS hides a "sort of" answer in the "Explanatory Notes" page of its web release. It's Note 51. The proportion of last year's babies who were first children was 43.8%, meaning most of the babies were second or subsequent children. (By the way 1.3 per cent of the babies joined five or more sisters or brothers)
Its a "sort-of answer" because it "excludes births registered in Victoria, Queensland and Tasmania". That's because those states don't collect information on how many previous babies the mother has had, only how many the father has had (including those in earlier relationships).
Given that it is the mother who has the children, the Victorian, Queensland and Tasmanian idea of what constitutes a second or a third seems strange (and certainly won't be used by the government in deciding what size baby bonus to grant).
Will they change it? Probably not? Is the ABS stuck with what it gets from the births deaths and marriages registries? Probably.
But wait. ANU demographer Peter McDonald says the Australian Institute of Health and Welfare has a much better data set it complies at the hospitals from nurses and midwives who actually ask each new mother how many children she has previously had. But it's late. The most recent publication is for 2009. It's also a magnificent source of data, far better than the ABS publication. It details the length of stay in hospital, everything - even the most popular month for births, which is October.
Peter Martin is economics correspondent for The Sydney Morning Herald and The Age.