Early Maternal Employment and
Children’s Cognitive and Social
Development:
Evidence from the Millennium Cohort Study
Denise D. Hawkes
15th July 2008
following lives from birth and through the adult years
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Outline of Presentation
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Research questions
Data
Model of early maternal employment
Results of determinants of early maternal employment
Model of child outcomes
Results of child outcomes
More on selection
Conclusion
following lives from birth and through the adult years
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Main Research Question

Interested in the impact of early maternal employment on child
cognitive development
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HOWEVER: Which mothers are employed?
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What are the characteristics of those who return to employment?
Are these different from those who do not return to employment?
Do these differences explain the difference in child outcomes
observed?
Therefore this paper will consider firstly the determinants of
maternal employment and then taking these determinants into
account the impact of early maternal employment on child
cognitive and behavioural development
following lives from birth and through the adult years
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The impact of government policy

One of the possible determinants of early maternal
employment especially in the early months of life is
government policies such as:
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Maternity Leave/Paternity Leave
Child care provision
Flexible working agreements/Parent friendly practices
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UK Policy Context
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Statuary Maternity Leave
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Statuary Paternity Leave
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First 4 months statutory maternity pay and an
additional 3 months unpaid job protected leave for
mothers who have completed one year full service.
2 weeks paid leave
Sure Start
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government programme aimed at bring together, early
education, childcare, health and family support
through their children’s centres which are mainly
located in disadvantaged areas in England
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What do this policy context suggest?

In UK those in employment before the birth of their
child are likely to return to employment 4-7 months
after the birth of their child
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There maybe interesting differences with the UK as only
England has Sure Start
Also the determinates of being in employment prior to
birth are also likely to be important
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Millennium Cohort Study
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The MCS is a nationally-representative sample of
18,818 babies within 18,552 families
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The cohort members were born in the UK between
September 2000 and January 2002 and were living in
selected UK wards at age 9 months
The sample was drawn to over-represent those who live
in areas of high child poverty, areas of high
concentrations of ethnic minorities and the Celtic
countries of the UK
The first sweep was undertaken when the cohort
members were 9 months old, the second when they
were 3 years old
following lives from birth and through the adult years
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MCS Descriptive Statistics – Month of
employment
For Natural Mothers
MCS
0-3 months
6%
4-5 months
24%
6-9 months
19%
Not by 9 months
51%
Observations
following lives from birth and through the adult years
18389
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MCS Descriptive Statistics – Month of
employment by education level
For Natural
Mothers
0-3 months
No
qualifications
6%
Up to A-Levels
Degree plus
15%
12%
4-5 months
8%
23%
33%
6-9 months
7%
11%
19%
Not by 9
months
79%
51%
36%
1737
7651
4591
Observations
following lives from birth and through the adult years
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Determinants of early maternal employment model
emp = α + β1child + β2 mother + β3 familyregion+ ε
where
emp is a dummy for whether the mother has returned to work by the time
the cohort child is 9 months
child is a selection of child characteristics‘ for example being the first born
child
mother is a selection of mother characteristics’ for example their level of
education
familyregion is a selection of family characteristics’ for example if they live
in owner occupied accommodation and a set of regional dummies
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Child Characteristics’
MCS
Child Characteristics’
First Birth
1.157
(1.044 - 1.256)**
Multiple Birth
0.558
(0.378 - 0.824)**
Low Birth Weight
0.809
(0.661 - 0.990)*
following lives from birth and through the adult years
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Mother Characteristics’
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Most likely to enter employment by 9 months if:
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MCS
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between 20-34 years old at the time of birth
hold qualifications
black ethnic group, not Pakistani or Bangladeshi
AND if employed one year prior to birth of the cohort child
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Family Characteristics’
MCS
Partnership status: reference married
Single
0.514
(0.438 - 0.603)**
Cohabiting
1.028
(0.921 - 1.147)
Number of other children in the household
0.924
(0.863 - 0.989)*
Other adults excluding parents in household
1.405
(1.196 - 1.651)**
Owner occupied housing
1.630
(1.445 - 1.839)**
following lives from birth and through the adult years
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Region
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MCS
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London mothers are the least likely to enter
employment by nine months
Mothers in the West Midlands and Yorkshire &
Humberside are the most likely to enter employment by
nine months
following lives from birth and through the adult years
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Early employment and developmental measures
at 9 months for MCS
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Those who have return to part time or full time
employment relative to those who have not worked in
the first 9 months of their child’s life report
significantly:
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more likely their children sleep through the night
more likely their children can sit up
more likely to be able to pass things from hand to hand
less likely to nod
following lives from birth and through the adult years
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Child outcomes & maternal employment
childout = α + β1emp+ 2child + β3 mother + β4familyregion+ ε
where
childout is the standardised BAS, Bracken or SDQ score at 3 years old
emp is a two dummies for whether the mother has returned to work full
time/part time by the time the cohort child is 9 months
child is a selection of child characteristics‘ for example being the first born
child
mother is a selection of mother characteristics’ for example their level of
education
familyregion is a selection of family characteristics’ for example if they live
in owner occupied accommodation and a set of regional dummies
following lives from birth and through the adult years
www.cls.ioe.ac.uk
BAS
Just considering
employment
Controlling for all
selection variables
Reference: no employment by 9 months
0-3 months
0.16
(0.03)***
-0.03
(0.03)
4-6 months
0.27
(0.03)***
0.30
(0.03)***
11505
-0.02
(0.03)
-0.01
(0.03)
11505
7-9 months
Observations
following lives from birth and through the adult years
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BAS continued
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Just working variables working returning to employment
in the first nine months of life is significantly positive
Moderated by the inclusion of child characteristics,
although they remain significantly positive
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Including mother’s characteristics, become insignificant
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largest and most significant covariates are first born,
breastfeed and birth weight
biggest and most important effect from maternal
education, more education higher scores for children
Including family and area characteristics, all remain
insignificant
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BAS continued part 2
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Heckman selection model
 Subgroups:
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no education, just working variables significantly
positive for returning after 4 months, with all variables
all insignificant
basic education, just working variables all significantly
positive, with all variables all insignificant
higher education, just working variables only
significantly positive between 7 and 9 months, with all
variables all insignificant
following lives from birth and through the adult years
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Bracken
Just considering
employment
Controlling for all
selection variables
Reference: no employment by 9 months
0-3 months
0.13
(0.02)***
-0.05
(0.03)
4-6 months
0.26
(0.03)***
0.34
(0.04)***
10980
-0.06
(0.03)**
-0.03
(0.03)
10980
7-9 months
Observations
following lives from birth and through the adult years
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SDQ
Just considering
employment
Controlling for all
selection variables
Reference: no employment by 9 months
0-3 months
4-6 months
7-9 months
Observations
-0.12
(0.03)***
-0.23
(0.02)***
-0.25
(0.03)***
0.04
(0.03)
0.04
(0.02)
0.06
(0.03)
12050
12050
following lives from birth and through the adult years
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Subgroup selection paths
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Employment positively linked:
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no educational qualifications
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GCSE and A-Levels
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to not first born, not being Bangladeshi, being a home
owner, having a partner and prior employment
not being a multiple birth, not being Bangladeshi, being
black, being a home owner, having an employed partner,
not being a student and prior employment
University
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not being a multiple birth, being a home owner, having a
partner, not having an employed partner and prior
employment
following lives from birth and through the adult years
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Conclusion
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Selection into the labour market after birth
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Impact of selection when explaining the relationship
between child outcomes and early maternal
employment
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Other things to consider

Link to other two papers
following lives from birth and through the adult years
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www.cls.ioe.ac.uk
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