The Relationship between Childbearing and Transitions from Marriage and Cohabitation in Britain

1
The Relationship between Childbearing and
Transitions from Marriage and Cohabitation in
Britain

• Fiona Steele1, Constantinos Kallis2, Harvey
  Goldstein1 and Heather Joshi3
• 1University of Bristol,2LSHTM, 3Institute of
  Education

2
Research Questions

• What is the link between partnership (marriage or
  cohabitation) stability and childbearing?
• Allow for joint determination of partnership and
  fertility processes
• Consider effects of presence and characteristics
  of children and pregnancy

3
Key Findings from Previous Research

• Having children together lowers the risk of
  dissolution for married couples, but there is
  little evidence of an effect among cohabitees
• Among cohabitees, having children is associated
  with decreased odds of marriage in GB and Canada,
  but increased odds in US (Manning Smock). Sharp
  increase in odds of marriage during pregnancy

4
Endogeneity of Prior Fertility Outcomes

• Interested in effect of presence of children on
  partnership transitions. But children are prior
  outcomes of a potentially correlated process
  (fertility).
• There may be factors (some unobserved) which
  influence decisions about partnership transitions
  and childbearing. If ignored, estimates of
  effects of interest will be biased.

5
Methodology used in Previous British Studies

• Most consider 1st partnership only
• Those using NCDS look at transitions for ages
  16-33 (e.g. Kiernan Cherlin 1999 Berrington
  2001)
• Transitions from marriage and (unmarried)
  cohabitation usually modelled separately
• Prior fertility outcomes usually treated as
  exogenous

6
Our Methodological Approach

• Consider all partnerships for ages 16-42 using
  multilevel modelling
• Estimate simultaneously models for 3 types of
  partnership transition
• Marriage ? Separation
• Cohabitation ? Separation Cohabitation ?
  Marriage
• Estimate these transitions jointly with model for
  fertility to allow for potential endogeneity of
  fertility outcomes

7
Joint Modelling of Partnership Transitions and
Fertility

• Our research builds on US study (Lillard Waite
  1993) which used a multiprocess model to allow
  for possibility that the processes of divorce and
  childbearing are jointly determined
• BUT only marital unions were considered
• We extend their approach to include outcomes of
  cohabiting partnerships
• Another British study (Aassve et al. 2006) also
  models union dissolution and fertility jointly,
  but groups together marriage and cohabitation.
  Recent US studies combine cohabitation and single

8
Methodology Overview

• Multilevel data structure repeated partnerships
  and births (level 1) within individuals (level
  2).
• Use multilevel multistate discrete-time event
  history model (Steele et al. 2004) for
  partnership transitions.
• States are marriage and cohabitation
• Competing risks from cohabiting state
• Estimate jointly with model for conceptions
  within partnerships using simultaneous equation
  (multiprocess) model (extending Lillard (1993)
  who considers only marriage).

9
Multilevel Modelling

• Some women have gt 1 partnership and/or conception
• May be unobserved characteristics which influence
  risk of all partnership transitions/births
• Leading to correlation between durations of
  partnerships/birth intervals for the same woman
• In a multilevel model, include random effects for
  each type of transition. These represent
  unobserved time-constant variables
• Correlation between random effects for different
  transitions are of substantive interest

10
Multiprocess Model of Partnership Transitions and
Fertility
11
Data

• 1958 British birth cohort (National Child
  Development Study)
• Partnership (living together for gt1 month) and
  birth histories collected retrospectively at ages
  33 and 42. Linked to form history for age 16-42.
• Covariates from childhood and adulthood.
• Analysis sample n5142 women with ?1 partner by
  age 42 n7032 partnerships and n9137
  partnership episodes.

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Measures of Prior Fertility(All Time-Varying)

• Current pregnancy status
• Number of preschool and older children living
  with respondent
• Distinguish between children fathered by current
  and previous co-resident partners, and those from
  non co-resident relationships

13
Other Explanatory Variables

• Previously married/cohabited
• Age at start of partnership
• Partnership duration
• No. years of education (time-varying)
• Paternal social class
• Family disruption before age 16
• Region of residence at birth
• Housing tenure at birth

14
Years to Partnership Transition Quartiles
15
Cross-Process Residual Correlations ( denotes
significance at 5 level)

• Separation from marriage and marital conception
• r -0.07 (-0.28 before accounting for current
  pregnancy)
• Separation from marriage and cohabiting
  conception
• r 0.42
• Separation from cohabitation and cohabiting
  conception
• r 0.32
• Cohabitation to marriage and cohabiting
  conception
• r 0.30 (0.43 before accounting for current
  pregnancy)

16
Effects of Fertility Variables on Log-odds of
Marital Separation
17
Effects of Fertility Variables on Log-odds of
Separation vs. Staying Cohabiting
18
Effects of Fertility Variables on Log-odds of
Marriage vs. Staying Cohabiting
19
Further Work Under Research Methods Project

• Comparison of effects of having children on
  cohabitation outcomes for 1958 and 1970 birth
  cohorts
• Effect of having children on partnership
  formation and outcomes for 1970 cohort

20
Cohort Comparisons for Cohabitation
Outcomes(1958 and 1970 cohorts, age 16-30)

• Sharp fall in proportion legalising
  cohabitation during pregnancy
• In 1970 cohort only, evidence of stabilising
  effect of having children together (lower risk of
  dissolution)
• But having school-age child from previous
  partnership reduces odds of marriage in 1970
  cohort

21
Effects of Fertility on Partnership
Formation(1970 cohort, age 16-30)

• Pregnancy hastens cohabitation and marriage among
  single women
• Presence of preschool child from previous
  partnership inhibits cohabitation among single
  women
• Presence of a school-age child from previous
  partnership inhibits marriage (among both single
  and cohabiting women)

22
Publications

• Steele, F., Kallis, C., Goldstein, H. and Joshi,
  H. (2005) The Relationship between Childbearing
  and Transitions from Marriage and Cohabitation in
  Britain, Demography, 42 647-673.
• Steele, F., Joshi, H., Kallis, C. and Goldstein,
  H. (2006) Changing Compatibility of Cohabitation
  and Childbearing between Young British Women born
  in 1958 and 1970, Population Studies 60(2)
  137-152.
• Steele, F., Kallis, C. and Joshi, H. (2006) The
  Formation and Outcomes of Cohabiting and Marital
  Partnerships in Early Adulthood The Role of
  Previous Partnership Experience, Journal of the
  Royal Statistical Society, Series A 169(4)
  757-779.