Social Polarisation in the timing of First Birth

following lives from birth and through the adult years www.cls.ioe.ac.uk

Examining the truth behind the myth of the 'the Monstrous Army on the March'

Dylan Kneale & Heather Joshi

Institute of Education

Social Polarisation in the timing of First Birth


Background I

Recognition that rates of transition to parenthood are decreasing - Men and women are postponing parenthood or avoiding parenthood altogether.

Known patterns of social polarisation in age at first birth. Early parenthood associated with a range of negative predictive characteristics and outcomes for parents and children.

Recent interest has focussed upon role of education in determining rates of transition to parenthood.

In particular, education differentials have been isolated as markers of increasing polarisation in age at first birth.


Background II


Background & Aims (Wolf): Graduate women = 'the Monstrous Army on the

March' What about graduate men – monstrous army still marching? Focus has been on increasing polarisation and rising

childlessness – but several different scenarios possible In addition are differentials caused by different sample

composition within groups, postponement or genuine decreased levels of transition?

Aims: Explore polarisation within and between two birth cohorts Examine the situation for males – increasing polarisation

too? Examine some of the determinants of fertility differentials


Data I

Analysis will use data from two British Birth Cohorts – National Child Development Study (NCDS, 1958) and the British Cohort Survey (BCS70, 1970).

Both studies began as a census of all UK births in a week, with additions in childhood waves.

In total, data for 18,558 and 18,731 collected at some point for NCDS and BCS70 respectively.

Attrition has affected both studies, with sample sizes at the last wave of data collection totalling around 9,500 for both.

However, population estimates of fertility transition appear consistent with external data (for women)

Comparison of Birth Cohort Motherhood Rates with National Statistics estimates for England and Wales

82%84%

73%

71%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Age

Pro

portio

n en

tering

mot

herh

ood

1958 National Statistic

1958 NCDS

1970 National Statistics

1970 BCS70


Data II1965

NCDS (Age 7)

1969 NCDS

(Age 11)

1970 BCS70 Birth

1974 NCDS

(Age 16)

1975 BCS70 (Age 5)

1981 NCDS

(Age 23)

1980 BCS70

(Age 10)

1986 BCS70

(Age 16)

1991 NCDS

(Age 33)

1996 BCS70

(Age 26)

2000 NCDS

(Age 42)

2000 BCS70

(Age 30) 2004

BCS70 (Age 34)

2004 NCDS

(Age 46) 1958 NCDS Birth


Changes in Sample Composition Twelve year gap between cohorts has meant both were born

into very different British societies (Wadsworth, Ferri et al. 2003). In particular, large changes in educational achievement.

BCS70

Intermediate Qualifications,

59%

Graduate Level, 36%

No Qualifications,

6%

NCDS

Graduate Level, 28%

No Qualifications

, 13%

Intermediate Qualifications

, 59%


Entry into parenthood: Overall cohort populations

Similar proportions of early parents exist in both cohorts. Differences open up in early and mid twenties so that by 34 years:

Gender ♂ ♀Cohort

NCDS (N =

7,142)

BCS70 (N =

5,862)

NCDS (N = 7,034)

BCS70 (N = 6,062)

Parents at Age 20 years 3.9% 3.2% 12.8% 10.1%




Highest educational level as a marker of polarisation

Qualifications at age 33/34 years

♂ ♀

Tertiary Level

NCDS (N = 1,727)

BCS70 (N = 2,108)

NCDS (N = 1,550)

BCS70 (N = 2,301)


Parents at Age 34 years

61.4% 44.2% 64.6% 57.7%

IntermediateNCDS

(N = 3,261)BCS70

(N = 2,511)NCDS

(N = 3,459)BCS70

(N = 2,716)



69.9% 57.2% 80.6% 75.6%

NoneNCDS

(N = 686)BCS70

(N = 285)NCDS

(N = 824)BCS70

(N = 245)



71.7% 60.4% 88.0% 81.3%


Predicting future trends

Numerous different approaches for predicting future trends based on existing levels of polarisation. Five approaches used in the next part:

1. NCDS parenthood

2. Postponed NCDS parenthood

3. Flight from parenthood

4. Covariate specific flight from parenthood

5. Covariate specific postponed flight from parenthood (!)

….and bringing in intentions later.


Results I: Tertiary Qualified Women

23.4%

33.9%33.2%28.8%

22.9%

28.0%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Age

NCDS Tertiary Qualified Females

BCS70 Tertiary Qualified Females:Flight from Parenthood

BCS70 Tertiary Qualified Females:Covariate Specific Flight fromParenthoodBCS70 Tertiary Qualified Females:NCDS Parenthood Rates

BCS70 Tertiary Qualified Females:Postponed NCDS Parenthood Rates

BCS70 Tertiary Qualified Females:Covariate Specific Postponed Flightfrom Parenthood


Results II: Tertiary Qualified Men

21.7%

40.6%40.1%

29.1%

22.6%

34.7%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Age

NCDS Tertiary Qualified Males

BCS70 Tertiary Qualified Males: Flight fromParenthood

BCS70 Tertiary Qualified Males: CovariateSpecific Flight From Parenthood

BCS70 Tertiary Qualified Males: NCDSParenthood Rates

BCS70 Tertiary Qualified Males: PostponedNCDS Parenthood Rates

BCS70 Tertiary Qualified Males: CovariateSpecific Postponed Flight From Parenthood


Results III: Intermediate and No Qualifications

Cohort and Projection Method

Intermediate Qualificati

ons

No Qualificati

ons

♂ ♀ ♂ ♀Childle

ss at 45

Childless at 45

Childless at 45

Childless at 45

NCDS 20.5%

13.9%

24.3%

10.5%

BCS70 – NCDS Parenthood Rates 29.8%

18.0%

32.0%

16.7%

BCS70 – Postponed NCDS Parenthood Rates

21.7%

13.5%

24.1%

11.0%

BCS70 – Flight from Parenthood 35.0%

19.7%

33.9%

17.6%

BCS70 – Covariate Specific Flight from Parenthood

35.0%

19.6%

34.3%

17.7%

BCS70 – Covariate Specific Postponed Flight from Parenthood

28.5%

15.5%

27.9%

13.1%


Increasing rates of polarisation? Distinctive patterns of parenthood based on educational

achievement in both cohorts. For women, relative proportions entering motherhood by

highest qualification level expected to stay constant – childlessness expected to rise gradually among all groups.

For men, gap in fatherhood rates between education levels is projected to change in some scenarios.

Gap between tertiary qualified and males with no and intermediate qualifications could widen–myth of monstrous women replaced by monstrous male graduates?

Gap between males with no and intermediate qualifications could narrow.


Tertiary Qualified I: Vocational Vs Academic

Cohort and Projection Method

♂ ♀Childles

s at 45 -

Academic

Childless at 45 -

Vocational

Childless at 45 -

Academic

Childless at 45 -

Vocational

NCDS 24.8% 17.1% 26.7% 19.1%

BCS70 – NCDS Parenthood Rates

28.2% 23.6% 27.8% 20.3%

BCS70 – Postponed NCDS Parenthood Rates

25.6% 22.3% 26.5% 17.5%

BCS70 – Flight from Parenthood

37.1%*32.9%*

*30.5%*

**22.4%*

**

BCS70 – Covariate Specific Flight from Parenthood

37.3%*31.0%*

***** ****

BCS70 – Covariate Specific Postponed Flight from Parenthood

35.0%*25.7%*

*29.3%¹ 19.8%¹

*Using 19-32 observation time; **Using 16-32 observation time; ***Using 20-32 observation time; **** Cohort effect drops out of significance when introducing other covariates; ¹Unadjusted cohort effect is used;


Tertiary Qualified II: Subject of qualification

37%

45% 46%49%

64%

58%62%

45%41% 40%

55%

41%

51%

44%47%

40%

0%

10%

20%

30%

40%

50%

60%

70%

Education,Humanities andCreative Arts

Science, Maths,Technology, Health,

Social Care,Medicine

Social Sciencesincluding Business,Finance and Law

Other MiscVocational Subjects

NCDS Males

BCS70 Males

NCDS Females

BCS70 Females

•Childlessness at 34; results for academic graduates


Measuring Postponement and Infertility Information on intentions to bear children and infertility of cohort

member and/or partner collected in both cohorts. This information gives the first indications that BCS70 cohort is

postponing as opposed to avoiding parenthood.

NCDS

Infertile/ Partner Infertile, 10.3%

Fertile and Categorically not children,

26.0%

Fertile and Open to

having more children, 16.1%

Fertile and don't know intentions,

13.3%

Fertility Intentions

and Infertility Status

Unknown, 34.2%

BCS70

Fertile and Open to

having more children, 46.1%

Infertile/ Partner

Infertile, 8.9%

Fertile and Categorically

not want children, 22.0%

Fertile and don't know intentions,

16.9%

Fertility Intentions and

Infertility Status

Unknown, 6.1%


Results IV: The impact of postponement – Tertiary Qualified Males

21.7%

29.8%25.7%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45

Age

Pro

por

tion

Entrin

g F

ather

hoo

d

NCDS Tertiary Qualified Males(Observed)

BCS70 Tertiary Qualified Males(Unadjusted)

BCS70 Tertiary Qualified Males(Adjusted for Postponement andInfertility)


Results V: The impact of postponement – Tertiary Qualified Females

23.4%

28.7%25.1%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45

Age

Pro

portio

n E

ntrin

g M

oth

erhood

NCDS Tertiary QualifiedFemales Observed

BCS70 Tertiary QualifiedFemales (Unadjusted)

BCS70 Tertiary QualifiedFemales (Adjusted forPostponement and Infertility)


Conclusions I

Social Polarisation is evident in age at first birth. Higher education levels obtained are correlated with later

transition to parenthood. Delay appears to have affected males with tertiary

qualifications disproportionately. Populations stratified by education level are not

homogeneous between cohorts. Partial estimates that do not fully take postponement and

infertility into account predict higher rates of childlessness for all populations stratified by education level.


Conclusions II When postponement and infertility are factored in, projected

childlessness could actually drop. Polarisation remains in age of transition although attenuated for final transition rates.

However, this could well be offset by higher rates of unintended childlessness.

Mirowsky (2005) suggests 34 years to be the optimum age for childbearing taking into account socioeconomic and biological factors.

In terms of intentions at least, little truth in ‘monstrous army on the march’ for women (or men).

Future Work: Project flight from parenthood scenario using infertility and

postponement information

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Social Polarisation in the timing of First Birth

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