The Predictors and Consequences of Early Parenthood

PhD Student: Dylan KnealeSupervisors: Professor Heather Joshi & Dr Jane Elliott Centre for Longitudinal Studies, Institute of Education,

University of London

• UK demography witness to decreasing fertility rates. • Age at first birth consistently increasing – in just 15 years,

between 1985 and 2000, the age at first birth rose from 25.9 to 29.1 years¹.

• One of a set of demographic changes characteristic of the ‘Second Demographic Transition’ (SDT)

• A number of explanatory theories for demographic transition that revolve around either economic or cultural change or both.

• Particular recent interest in young age at first birth as it is a recognised marker of disadvantage.

• However, confusion if young age at first birth purely a marker of existing disadvantage (Geronimus 2003; Goodman 2004) or a cause of future disadvantage (SEU 1999).

¹United Nations Economic Commission for Europe 2002

Background

Background

Chart 1: Age at first birth and

household income (Age 16)

Chart 2: Age at first birth and

household income (Age 46)

• In line with these theories, the timing of parenthood can be viewed as an economic and cultural adaptation to local circumstances.

• A wide body of evidence exists on the predictors of early motherhood. Less interest in the timing of fatherhood.

• Known predictors include educational attainment, socioeconomic measures of family background and personal characteristics among others.

• However, according to some demographic theories, contextual influence is highly significant in the timing of parenthood, although this area comparatively unexplored.

Background

1) When should parenthood be thought of as being early?

2) How many people experience early parenthood?

3) What are the factors that predict early parenthood?

4) To what extent do contextual factors predict early parenthood?

5) Do these contextual factors affect the outcomes of parents and children?

Research Questions

Utilise strengths of the birth cohort studies to examine factors affecting fertility.

• National Child Development Study (NCDS) – Originally included all live births in G.B from one month in 1958.

• British Cohort Study (BCS70) – Originally included all live births in U.K from one month in 1970.

• In both studies, the addition of immigrants has been offset by attrition:

Data

Cohort Original Sample

No. ever involved

Previous (2004) Sample

NCDS 17,634 18,558 9,534

BCS70 16,572 17,287 9,665

1958 NCDS Birth

1965 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)

Data Collection NCDS

Data Collection BCS70

•What is early parenthood?

•Early parenthood synonymous with teenage parenthood in media

•Is this meaningful distinction or just convention?

•Age specific fertility rate for teenagers decreased from 30 births per 1000 women in 1985 to 26 births per 1000 in 2005 (ONS)

•Is focus reactive to media and political constructions or real differences?

•What is early parenthood?

Number of Articles by Definition of Motherhood with UK Birth Trends

0

5

10

15

20

25

30

35

40

45

50

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006Year of Publication

Num

ber

of

Art

icle

s

24

25

26

27

28

29

30

31

32

Age

Speci

fic

Fert

ilit

y

Rate

- B

irth

s per

1000

wom

en

Teenage Motherhood

Early Motherhood

Age Specific FertilityRate - Teenagers

Thinking about defining parenthood…..

How should early parenthood be defined?

i

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n

dntS )(

•Using absolute cut off points, survival analysis and piecewise regression to derive definitions of early parenthood:

•The literature supports the idea that the effects of the timing of parenthood are felt up to a certain point, changing after this. Piecewise regression methods are used to test this proposition.

How should early parenthood be defined – example output…..

Household Income Age 46 Coef. (£) P>|t|[95% Conf.

Interval]

age1 1201.2 0.000 884.2 1518.2

age2 -1487.7 0.001 -2343.5 -632.0

_cons 15802.2 0.000 7515.0 24089.5

•In the above output, a spline has been identified at age 32. Up to this age, delaying fatherhood corresponds to an increase in household income of value age1 (However, other factors do mitigate the relationship)

• Age2 corresponds to the value of the difference between slopes up to 32 years and ages afterwards – significantly different

How could early fatherhood be defined?

Birth

14 years 5 months, first

NCDS father

15 years 2 months, first

BCS70 father

Teenage

23 years 11 months, first

12.5% of BCS70

cohort are fathers

21 years 2 months, first

12.5% of NCDS

cohort are fathers

24 years 11 months, first

25% of NCDS

cohort are fathers

27 years, first 25% of

BCS70 cohort are

fathers

27 years spline

identified from NCDS

cm’s mother’s

age at first birth

28 years spline

identified from NCDS test scores

32 years spline

identified from NCDS

income

Conclusion: Teenage definition is a poor definition of early fatherhood. Given the data, a proportional definition is satisfactory

How could early motherhood be defined?

Birth

13 years 2 months, first

NCDS mother

15 years 2 months, first

BCS70 mother

Teenage

20 years 8 months, first

12.5% of BCS70

cohort are mothers

19 years 11 months, first

12.5% of NCDS

cohort are mothers

22 years 2 months, first

25% of NCDS

cohort are mothers

23 years 11 months, first

25% of BCS70

cohort are mothers

27 years spline

identified from NCDS

cm’s mother’s

age at first birth

28 years spline

identified from NCDS test scores

33 years spline

identified from NCDS

income

Conclusion: Teenage definition is a poor definition of early motherhood. Given the data, a proportional definition is satisfactory

However, both studies have suffered from attrition – how representative are the cohort fertility patterns with

other sources?

Comparison of Birth Cohort Fertility with National Statistics for England and Wales

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45

Age

Es

tim

ate

d C

um

ula

tiv

e H

aza

rd

1958 National Statistic

1958 NCDS

1970 National Statistics

1970 NCDS

How many early parents feature in NCDS and BCS70? – the definitions to be used in the remainder of the research….

Gender DefinitionNCDS BCS70

No. Age No. Age

♂Teenage 278 <20 188 <20

First 12.5%* 892 21y 2m 735 23y 11m

First 25%* 1684 24y 11m 1466 27y

♀

Teenage** 903* <20 615 <20

First 12.5%* 885 19y 11m 761 20y 8m

First 25%* 1763 22y 2m 1519 23y 11m

Parents at 46Childless at 46*

(%)Parents at 34

Childless at 34* (%)

♂ Timing 4646 21% 2997 44%

♀ Timing 5304 16% 4060 30%

*Based upon KM estimates; **because this definition does not vary significantly from 12.5%, it will not be used extensively in further research

What do we know about the predictors of early parenthood?

Timing of Motherhood

Individual Factors

Contextual Factors

•Know from the literature that socioeconomic, educational, demographic and personal variables are significant predictors of the timing of parenthood in addition to contextual effect.•These variables will form controls in models that test the residual contextual effects•Neighbourhood data available as census variables with diverse indicators such as % married women working and % with indoor bathroom at 2 levels of geography

Neighbourhood factors as predictors of early parenthood (I)

• Due to the nature of the birth cohort studies, no complex modelling needed to capture neighbourhood effects in BCS70 and NCDS (such as MLM). Models below could be used with inclusion of individual level measure to avoid ecological fallacy

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ΤZtzt exp*)()|( 0HOWEVER…….

Neighbourhood factors as predictors of early parenthood (II)Despite limitations, after controlling for known confounders and individual

measurements, some conclusions can be drawn:• Neighbourhood found to exert a small but significant effect on fertility• Some more cultural measures of neighbourhood such as % of immigrants; %

of population aged 0-4 years and % of married women working highly insignificant.

• In general, neighbourhood effects appear to exert a stronger influence on the timing of fatherhood than motherhood, although significant results found for the timing of motherhood

• Social class measurements on the local authority level more likely to influence the timing of fatherhood

• Tenure measurements on the enumeration district level more likely to influence the timing of motherhood

• Some indication of gender-occupation interactions found with certain variables (e.g. % of workforce in mining and manufacturing)

Neighbourhood factors as predictors of early parenthood (III)

Covariate

Early Fatherhood vs Later Fatherhood

Very Early Fatherhood vs Later Fatherhood

Odds Ratio Odds Ratio

Professional and Managerial (% in Local Authority)

0.96** 0.95**

Social Class (Baseline Social Class V)  

Social Class I 0.41* 0.22*

Social Class II 0.60 0.49*

Social Class III 0.77 0.57

Social Class IV 0.92 0.80

Tenure (Baseline Owner Occupation)  

Council Housing 1.91** 2.41**

Privately Rented 0.85 0.62

Tied and other forms 2.28** 2.15*

Educational Achievement Age 11 0.74** 0.80**

*p<0.05; **p<0.01; BS = Borderline significant (p>0.05 P<0.07)r² =

Covariate

Early Motherhood vs Later

Motherhood

Teenage Motherhood vs

Later Motherhood

Very Early Fatherhood vs Later

Fatherhood

Odds Ratio Odds Ratio Odds Ratio

Unskilled (% at Local Authority) 1.067* 1.087** 1.087*

Social Class (Baseline Social Class V)

Social Class I 0.180* - 0.216**

Social Class II 0.460 0.470* 0.476**

Social Class III 0.493 0.682 0.565

Social Class IV 0.188 0.788 0.644

Tenure (Baseline Owner Occupation)

Council Housing 1.63** 1.387 1.970**

Privately Rented 0.875 1.404 0.600

Tied and other forms 0.952 2.977 2.103*

Educational Achievement Age 11 0.770** 0.724 0.782**

Parental Age at First Birth 0.968** X X

Parental Structure (Baseline No Natural Parents)

1 Natural Parent X 4.134* X

2 Natural Parents X 2.264 X

Parental Interest in Education (No Parent with Healthy Interest)

Both Parents Healthy Interest 0.427** 0.569** X

1 Parent with Healthy Interest 0.866 1.062 X

*p<0.05; **p<0.01; BS = Borderline significant (p>0.05 P<0.07); Standard errors in brackets; X = Covariate insignificant and not included in parsimonious model

Other Contextual factors as predictors of early parenthood

Because of the limitations in exploring neighbourhood (census) variables further, a broader definition of context adopted will be adopted.

In particular this will explore the concept of resilience by looking at the environment provided by parents not directly associated with socioeconomic factors.

Preliminary work into parental interest in education reveals this to be significant predictor of fertility patterns net of socioeconomic factors.

A number of measures of family life remain unexplored.

Future DirectionsImmediate:• Conclude neighbourhood measurements section and change modelling

strategy for the timing of parenthood (survival) variables: theoretically and empirically problematic.

• Continue exploratory analysis of parental environment variables and explore their significance as predictors.

Mid-term:• Decide on final modelling strategies for predictors• Conclude the effects of contextual factors on the timing of parenthoodLong-term:• Begin to examine the effects of these contextual factors and interactions with

age at first parenthood on the outcomes of mothers and children