“Being Educated or in Education:
the Impact of Education on the Timing of Entry into Parenthood”
Dieter H. Demey
Faculty of Social and Political Sciences
Queens’ College
University of Cambridge
United Kingdom
Structure of the presentation
1. Demographic background (1945-present)
2. Theoretical framework and previous empirical research
3. Hypotheses
4. Data and methodology
5. Results
6. Conclusions
2
1. Demographic background (1945-present) (1)
Trends:
1. Postponement of the transition to parenthood
2. Increase in the degree of childlessness
Link between the postponement of first births and increasing
childlessness:
 are postponed first births fully recuperated?
 degree of recuperation of first births?: births postponed are
births foregone
3
1. Demographic background (1945-present) (2)
proportion with at least one child
1.00
age 45
0.80
age 35
0.60
age 30
0.40
age 25
0.20
0.00
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
year of birth
England and Wales, 2006 (ONS, 2007)
4
2. Theoretical framework and previous empirical research (1)
Educational attainment is an important factor in explaining the timing of
first births and change over time:
a) Economic models of fertility (e.g. Becker, 1981):
 opportunity costs of childbearing and childrearing
 education ~ earning potential
b) Sociologists:
 incompatibility of motherhood and work
 education ~ labour market participation
c) Second demographic transition theory (e.g. Lesthaeghe, 1983, 1988):
 secularisation and individuation
 education ~ value orientations, preferences, aspirations
5
2. Theoretical framework and previous empirical research (2)
• Empirical research:
 positive relation between educational attainment and the timing
of first births
 educational attainment -> delaying effect on the transition to
parenthood
- However, results are dependent on whether educational activity and the
time elapsed since leaving the educational system are taken into account:
 educational activity: effect of educational attainment becomes
insignificant or reverses
 time elapsed since leaving education: reversed effect of
educational attainment: catch-up effect
- Gender-specific effects?
6
3. Hypotheses (1)
1. Educational attainment:
There is a positive effect of educational level on the timing of the first
birth. In other words, the lower educated are expected to accelerate the
entry into parenthood, while the higher educated are expected to
postpone the entry into parenthood
2. Educational activity:
There is a negative effect of enrolment in education on the rate of the
entry into parenthood. In other words, the entry into parenthood will be
postponed during the period of enrolment in education and will be
accelerated once persons leave the educational system
7
3. Hypotheses (2)
3. The time elapsed since leaving education:
There is a positive relation between educational attainment and the rate
of acceleration into parenthood after finishing education. In other
words, the time interval between leaving education and entering
parenthood is expected to decrease as the educational level increases
8
4. Data and methodology (1)
• British Household Panel Survey (BHPS)
• Waves 1 to 15 (1991-2006)
• Fertility: reconstructed first birth histories until the date of the last
interview:
 retrospective: fertility histories collected in wave 2
 prospective: first birth observed during the panel
• Education: highest educational qualification and the date of exit from
the educational system (first exit):
 retrospective: employment histories collected in wave 2
 prospective: exit observed during the panel
• Sample: women and men, birth cohorts 1930-1989, no missing
information
9
4. Data and methodology (2)
• Discrete-time hazard model:
 first births are measured in monthly intervals
• Complementary log-log model (“cloglog”): discrete-time representation
of a continuous-time proportional hazard model
 underlying process is in continuous time
• Risk set: age 14 until age 45
• No left-censoring
• Right-censoring:
 month of occurrence of the first birth
 or, at the date of the last interview / month 45th birthday
10
4. Data and methodology (3)
• Dependent variable: probability of a first birth
• Independent variables:
 enrolment in education: time-varying dummy variable, 1
indicating enrolment, 0 otherwise
 educational level: time-constant categorical variable with 6
categories
 time since leaving education: time-varying categorical variable
with 11 categories
• Final sample size women = 4968 / number of first births = 3164
• Final sample size men = 4666 / number of first births = 2468
11
5. Results (1)
Modelling the probability of the first birth (complementary log-log model)
HR
sig.
women
HR sig.
Educational level
no QF / enrolled at last interview (ref. cat.)
comp. school QF
post-comp. school QF (vocational) (16 onwards)
post-comp. school QF (academic) (16 onwards)
post-comp. school QF (vocational) (18 onwards)
post-comp. school QF (academic) (18 onwards)
0.66
0.66
0.52
0.58
0.38
***
***
***
***
***
0.66
0.65
0.54
0.59
0.45
Enrolment in education (1=in education)
--
0.08 ***
--
Time elapsed since leaving education
0 (still enrolled, 1=in education)
0-2 years (ref. cat.)
2-4 years
4-6 years
6-8 years
8-10 years
10-12 years
12-14 years
14-16 years
16-18 years
18+ years
------------
------------
0.12 ***
***
***
***
***
***
HR
sig.
0.77
0.69
0.68
0.71
0.66
***
***
***
***
***
1.63
2.39
4.25
4.91
5.33
4.91
4.60
3.80
3.36
***
***
***
***
***
***
***
***
***
12
5. Results (2)
Modelling the probability of the first birth (complementary log-log model)
men
HR sig.
HR
0.81
1.10
0.77
0.88
0.63
0.88 **
1.09
0.86 **
0.96
0.87 **
HR
sig.
Educational level
no QF / enrolled at last interview (ref. cat.)
comp. school QF
post-comp. school QF (vocational) (16 onwards)
post-comp. school QF (academic) (16 onwards)
post-comp. school QF (vocational) (18 onwards)
post-comp. school QF (academic) (18 onwards)
0.83
1.14
0.79
0.90
0.60
***
Enrolment in education (1=in education)
--
0.10 ***
--
Time elapsed since leaving education
0 (still enrolled, 1=in education)
0-2 years (ref. cat.)
2-4 years
4-6 years
6-8 years
8-10 years
10-12 years
12-14 years
14-16 years
16-18 years
18+ years
------------
------------
0.28 ***
***
*
***
***
***
**
***
1.85
3.02
4.42
6.34
7.51
6.09
5.87
5.21
4.28
sig.
***
***
***
***
***
***
***
***
***
13
5. Results (3): catch-up effect?
Modelling the probability of the first birth by separate age groups (complementary log-log model)
Women
14-17
HR sig.
17-20
HR sig.
21-25
HR sig.
26-30
HR sig.
31-45
HR sig.
Educational level
no QF / enrolled at last interview (ref. cat.)
comp. school QF
post-comp. school QF (vocational) (16 onwards)
post-comp. school QF (academic) (16 onwards)
post-comp. school QF (vocational) (18 onwards)
post-comp. school QF (academic) (18 onwards)
0.86
-0.17 *
0.57
0.47
0.56
0.49
0.36
0.46
0.24
0.56
0.57
0.47
0.48
0.29
1.01
1.15
0.94
0.96
0.81 *
1.21
1.24
1.20
1.30
1.40 *
Enrolment in education (1=in education)
0.10 ***
0.07 ***
0.12 ***
--
***
***
***
***
***
***
***
***
***
***
0.10 ***
14
5. Results (4): catch-up effect?
Modelling the probability of the first birth by separate age groups (complementary log-log model)
Men
14-17
HR sig.
17-20
HR sig.
21-25
HR sig.
26-30
HR sig.
31-45
HR sig.
Educational level
no QF / enrolled at last interview (ref. cat.)
comp. school QF
post-comp. school QF (vocational) (16 onwards)
post-comp. school QF (academic) (16 onwards)
post-comp. school QF (vocational) (18 onwards)
post-comp. school QF (academic) (18 onwards)
0.32
--0.71
--
1.59
0.81
0.33
0.55
0.21
0.73
0.95
0.57
0.63
0.23
0.84
1.26
0.93
1.11
0.81 **
1.04
1.40
1.47 **
1.40 **
1.61 ***
Enrolment in education (1=in education)
0.68
0.05 ***
0.12 *
0.31
**
***
***
***
***
***
***
***
0.09 ***
15
6. Conclusions (1)
• Educational attainment
 strong and positive effect of educational attainment on the
timing of first births
 postponement effect is stronger among women than among men
 differences between groups of education are larger among
women than among men
• Enrolment in education
 strong and negative effect of enrolment in education on the rate
of entry into parenthood
 effect of educational level on the hazard of first births does not
change (no pure mechanical effect of educational attainment)
16
6. Conclusions (2)
• The time elapsed since leaving education
 monotonous increase in the rate of entry into parenthood until 10
to 12 years after leaving the educational system
 effect of educational level becomes smaller
 catch-up effect among the higher educated after age 30
 effect is stronger among men than among women
17