Spacing of children in Switzerland constancy or change

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Spacing of children in Switzerland: constancy or change? Marion Burkimsher Affiliated to University of

Spacing of children in Switzerland: constancy or change? Marion Burkimsher Affiliated to University of Lausanne

Source BEVNAT

Source BEVNAT

Birth spacing - what and why? • Not difference in mean age of successive

Birth spacing - what and why? • Not difference in mean age of successive birth orders • Can obtain spacing data from surveys (or census data), but not birth registration by birth order • Why these are different…(women who end up having bigger families start childbearing at a younger age; women who start later have fewer children) • With birth spacing data (probability of subsequent birth knowing duration since last birth) - and female population by parity & age can make good TFR projections by Mc. Donald-Kippen method

Source BEVNAT

Source BEVNAT

Source BEVNAT

Source BEVNAT

Example of erroneous deduction: spacing in Switzerland FFS sample data from 1994 for women

Example of erroneous deduction: spacing in Switzerland FFS sample data from 1994 for women aged 40 -44 ie. cohorts 1950 -1954 Mean age at 1 st birth 26. 9 Mean spacing 1 st-2 nd child: 3. 13 years Mean spacing 2 nd-3 rd child: 3. 62 years Mean spacing 3 rd-4 th child: 3. 13 years Houle & Shkolnikov, 2006 then made the following incorrect deductions using age at 1 st birth as the starting point: Deduced mean age at 2 nd birth 30. 0 Deduced mean age at 3 rd birth 33. 6 Deduced mean age at 4 th birth 36. 8

Restating… We cannot deduce anything about birth spacing from differences in mean age at

Restating… We cannot deduce anything about birth spacing from differences in mean age at successive birth orders! We cannot deduce anything about mean age of successive birth orders from information on birth spacing! Why? Because women who have their first child at a younger age have more likelihood of having a larger family than women who start at a later age. This is easier to understand with an illustration…

2 hypothetical scenarios…

2 hypothetical scenarios…

Scenario 1: 4 women, having 1, 2, 3 and 4 children respectively 28 31

Scenario 1: 4 women, having 1, 2, 3 and 4 children respectively 28 31 34 25 Age Mean age at 1 st birth: 25 Mean age at 2 nd birth: 28 Mean age at 3 rd birth: 31 Mean age at 4 th birth: 34 Mean spacing between all birth orders: 3 years Mean age at last birth: 29. 5

Scenario 2: 4 women, having 1, 2, 3 and 4 children respectively 28 31

Scenario 2: 4 women, having 1, 2, 3 and 4 children respectively 28 31 34 25 Age Mean age at 1 st birth: 29. 5 Mean age at 2 nd birth: 31 Mean age at 3 rd birth: 32. 5 Mean age at 4 th birth: 34 Mean spacing between all birth orders: 3 years Mean age at last birth: 34

Hypothesis That between 1969 and the present time there has been a transition from

Hypothesis That between 1969 and the present time there has been a transition from Scenario 1 being the norm to Scenario 2. But we need birth spacing data…

Using data from SHP • Data about cohabiting children had to be combined with

Using data from SHP • Data about cohabiting children had to be combined with data on (older) children who had moved out of the household • Frequency curves of spacing are skewed; modal gap < median gap < mean gap • Likelihood of going on to a 2 nd / 3 rd child changes over time • Solution - survival analysis, life table method (as only whole year data) • Survival analysis gives: 1. change in intensity 2. change in ultimate likelihood 3. median duration of transition (if >50% experience it)

Interesting statistics from SHP sample Longest gap 1 st-2 nd for a woman is

Interesting statistics from SHP sample Longest gap 1 st-2 nd for a woman is 18 years Longest gap 1 st-2 nd for a man is 32 years Longest gap 2 nd-3 rd for a woman is 31 years! Longest gap 2 nd-3 rd for a man is 25 years Range, age at 1 st birth, woman - 15 -54 years Range, age at 1 st birth, man - 12 -59 years Range, age at 2 nd birth, woman - 17 -49 years Range, age at 2 nd birth, man - 16 -59 years …as men have no upper bound, only look at women’s rates …

Modal gap 1 st -2 nd & 2 nd 3 rd is 2 years

Modal gap 1 st -2 nd & 2 nd 3 rd is 2 years

Median gap % no 2 nd 1960 s 3. 3 20 1970 s 3.

Median gap % no 2 nd 1960 s 3. 3 20 1970 s 3. 5 18 1980 s 3. 3 17 1990 s 3. 3 18 2000> 3. 6 22 No significant change in 1 st-2 nd gap from 1960 s to present day!

But significant changes for 2 nd-3 rd child transition!

But significant changes for 2 nd-3 rd child transition!

How does age of mother affect spacing? …remembering that age at childbearing has been

How does age of mother affect spacing? …remembering that age at childbearing has been rising over time

Significantly less likelihood of women having a 2 nd child if over 35 when

Significantly less likelihood of women having a 2 nd child if over 35 when 1 st born

Very significant difference in likelihood of woman having 3 rd child if her 2

Very significant difference in likelihood of woman having 3 rd child if her 2 nd born before/after 30

Various potential determinants

Various potential determinants

Cannot yet confirm or deny hypothesis Initial investigations encouraging… SHP is only up-to-date data

Cannot yet confirm or deny hypothesis Initial investigations encouraging… SHP is only up-to-date data source on birth spacing in Switzerland More work to be done…

Spacing of children in Switzerland: constancy or change? • 1 st-2 nd child transition

Spacing of children in Switzerland: constancy or change? • 1 st-2 nd child transition > constancy • 2 nd-3 rd child transition > change (decline in likelihood)

Thank you!

Thank you!