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ARTICLE IN PRESS
0277-9536/$ - se
doi:10.1016/j.so
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Social Science & Medicine 61 (2005) 217–228
www.elsevier.com/locate/socscimed
Fertility history and health in later life: a record linkage studyin England and Wales
Emily Grundy�, Cecilia Tomassini
Centre for Population Studies, London School of Hygiene and Tropical Medicine, 49-51 Bedford Square, London WC1B 3DP, UK
Available online 4 February 2005
Abstract
Women born at different periods within the 20th century in England and Wales have followed varying fertility
pathways with large changes in, for example, proportions having no children or only one child. Among the
consequences of these changes may be effects on women’s health later in life. Links between fertility histories and later
health and mortality have been investigated in several studies, but in many of these socio-economic characteristics have
not been allowed for, even though there are socio-economic differences in both fertility and mortality patterns and
results are conflicting. Here we analyse associations between the fertility histories of women born 1911–1940 in England
and Wales and their mortality and health status after age 50. We used data from the Office for National Statistics
Longitudinal Study; a record linkage study of approximately 1% of the population initially based on those enumerated
in the 1971 Census of England and Wales. We used survival analysis to investigate the effects of parity, short birth
intervals, and timing of fertility on mortality from age 50 to the end of 2000, controlling for a range of relevant socio-
demographic characteristics. For survivors to 1991, we additionally used logistic regression to model probability of
having a limiting long-term illness in 1991. We found that nulliparous women and women with five or more children
had significantly higher mortality than other women, and that in the oldest groups women with just one child also had
raised mortality. Women who had been teenage mothers had higher mortality and higher odds of poor health than
other parous women. Mothers with short birth intervals, including mothers of twins, also had elevated risks in some
cohorts. Late childbearing (after age 39) was associated with lower mortality.
Personal demographic history is an important factor to consider in analyses of health and mortality variations in later
life. More research is needed to further elucidate causal pathways.
r 2005 Elsevier Ltd. All rights reserved.
Keywords: Women’s health; Reproductive history; Life course; Parity; Birth intervals; England and wales
Introduction
The importance of life course influences on health and
mortality differentials in later life is increasingly
recognised, both because past experiences exert strong
influences on current circumstances and because accu-
e front matter r 2005 Elsevier Ltd. All rights reserve
cscimed.2004.11.046
ing author. Tel.: +4420 7299 4668;
9 4637.
ess: [email protected] (E. Grundy).
mulated stresses may have long-term influences (Wads-
worth, 1997; Blane, 1999; Kuh & Hardy, 2002).
Parenthood represents a major domain of most people’s
lives with substantial short and long-term implications.
Apart from the physiological and psychological effects
of pregnancy and childbirth, the health of both women
and men may be influenced by stresses, role changes and
changes in allocation of personal and family resources
associated with childrearing and by the emotional and
social support benefits of parenthood. Whether the
d.
ARTICLE IN PRESSE. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228218
long-term balance of these influences has negative or
positive effects on health in later life is likely to depend
both on the fertility pathways followed and on the
context in which these take place. In this paper we
analyse associations between the fertility histories of
women in England and Wales born between 1911 and
1940 and their mortality and health status after the age
of 50.
Hypothesised links between fertility histories and health
There are a number of mechanisms which may
underlie associations between fertility histories and
health in later life. These include direct biological
effects, selection effects, and indirect effects such as the
relative costs and benefits of childrearing.
The direct effects of fertility on the later life health of
women include the physiological consequences of
pregnancy and childbirth. Apart from the risks of
childbirth itself, childbearing in historical populations
and contemporary less developed countries, has been
associated with risks of both short and long term
morbidity (Riley, 2003; Menken, Duffy, & Kuhn, 2003).
Additionally, there are well-established linkages between
some aspects of fertility patterns and certain diseases,
most notably breast cancer (associated with nulliparity
and delayed motherhood, Madigan, Ziegler, Benichou,
Byrne, & Hoover, 1995). More recently reproductive
histories have been linked with a range of later life
chronic diseases, although it is unclear whether repro-
ductive characteristics are risk factors for chronic
diseases in their own right or whether they ‘merely
reflect earlier exposures in childhood and adolescence
that are the direct determinants of chronic disease’(Rich-
Edwards, 2002).
Selection effects are undoubtedly important as socio-
economic characteristics are strongly associated with
nuptiality and fertility patterns on the one hand and
with health and mortality on the other, although both
the strength and the direction of these associations have
varied over time (Ni Bhrolchain, 1993; Donkin, Gold-
blatt, & Lynch, 2002). Possible ‘reverse causation’ effects
on fertility, including timing of motherhood, need
consideration as well. Poor health may restrict oppor-
tunities for marriage and parenthood and decisions
about subsequent childbearing (Kiernan, 1988, 1989).
Ability to conceive and deliver a child after the age of 40
may be an indicator of ‘slower’ ageing and overall better
health (Snowdon et al., 1989) and in some populations
variations in teenage fecundity, influenced by childhood
nutritional status, may also be relevant. The effect of
these selective processes will certainly have varied over
time and between social groups. For example, a
comparative study of teenage motherhood based on
analyses of the 1946 and 1958 British birth cohort
studies showed that teenage mothers in the later cohort,
when teen childbearing was rarer, had more unfavour-
able antecedent characteristics than in the 1946 cohort
(Maughan & Lindelow, 1997). Availability of medical
care and access to modern methods of birth control are
also likely to have resulted in important differences in
the operation of these selective processes.
Parenting experiences more generally may have
consequences for health. Parenting has many benefits,
but also costs. On the positive side parenthood may
enhance social networks, provide a positive social role
and a potential important source of social support,
especially in the longer term (Grundy & Shelton, 2001).
The costs of parenthood include reduced opportunities
for fulfilment of other roles, the stresses associated with
rearing children, and substantial economic costs (Gra-
ham, 1984; Joshi, 2002). The impact of these stresses is
likely to vary with socio-economic circumstances. For
example, research has shown high rates of depression
and stress in lone mothers but not in married mothers
whose mental and general health is better than that of
non-mothers (Harrison, Barrow, Gask, & Creed, 1999).
Certain fertility pathways, particularly early childbear-
ing and closely spaced births, may increase both
physiological and social and psychological stresses and
are known to increase risks of partnership disruption
which itself may have negative consequences for health
(Murphy, 1984).
Finally some evolutionary theories of ageing posit a
negative relationship between fertility and longevity
reflecting ‘trade offs’ in investment in younger-age
reproductive ‘fitness’ and somatic maintenance in the
post-reproductive period (Kirkwood & Rose, 1991).
Previous research on fertility patterns and health
Given the complexity of these hypothesised links
between fertility and health, it is perhaps not surprising
that results from empirical studies are in some respects
confusing or conflicting. These ambiguities may also
reflect the range of methods and populations studied
and inability in many of them to control for important
interactions with socio-economic and socio-demo-
graphic characteristics. Several studies of historical
populations have reported links between parity, espe-
cially high parity, and later life mortality. Westendorp
and Kirkwood (1998) reported a negative association
between number of children borne and mortality after
the age of 60 for both female and male members of the
English aristocracy, although concerns about the quality
of the data used in this analysis have been raised
(Gavrilov & Gavrilova, 2002). An analysis of the
mortality of Southern Californians born 1880–1929 also
showed a negative relationship between parity and
survival among women, but not men (Friedlander,
ARTICLE IN PRESSE. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228 219
1996). A study of Danish twins born 1893–1923 used
dentition at age 73 or over as the outcome measure
(tooth loss being a well established indicator of
cumulative nutritional strain) and found a positive
association between parity and tooth loss—those with
more children had fewer remaining teeth—and an
interaction with socio-economic status (Christensen,
Gaist, Jeune, & Vaupel, 1998). Other historical studies,
however, have found multiparous women had better
post menopausal survival than women with no or only
one child or that the direction of the association
depended on whether duration of marriage was taken
into account (Lycett, Dunbar, & Voland, 2000; Muller,
Chiou, Carey, & Wang, 2002).
Results from studies of more recent populations are
also sometimes conflicting. Some report higher mortality
among parous than nulliparous women; others the
reverse (Beral, 1985; Green, Beral, & Moser, 1988).
Several studies suggest nulliparity and high parity are
associated with higher risk (Kvale, Heuch, & Nilssen,
1994). These, include research by Doblhammer (2000),
whose analysis was based on Office for National
Statistics (ONS) Longitudinal Study data for England
and Wales and the 1981 Austrian census with linked 1
year follow up of deaths. However, this study was
restricted to ever-married women (as were several of the
others cited above) and the only socio-economic
indicator allowed for was presence/absence of higher-
level educational qualifications which is a poor dis-
criminator of socio-economic status in the current older
female population (Grundy and Holt, 2000). Moreover
only three parity groups were contrasted; the nullipar-
ous, those with one or two children, and mothers of
three or more children. Kington, Lillard, and Rogowski
(1997) in a study of a contemporary US population,
which they reported was the first in which associations
between reproductive history and health, rather than
mortality, were examined found that higher parity
women aged 50 and over had worse health compared
with nulliparous or low parity (1–2) women but
emphasised that their findings needed verification using
other data. Grundy and Holt (2000) using data from the
British ONS Retirement Surveys, found that parity was
associated with health and disability in early old age, but
sample size was relatively small and findings were
suggestive rather than conclusive.
Timing of childbearing, as well as number of children,
has been associated with health in later life in some
studies. Very early childbearing has been linked with a
range of negative outcomes, including poorer health
(Maughan & Lindelow, 1997) and, in poorer countries,
impaired growth (Riley, 1994). Few studies have looked
beyond health in early or mid life, although Grundy and
Holt (2000) found that self reported health among
women aged 55–74 was negatively associated with birth
before age 23 (taking account of socio-economic
circumstances) and in Doblhammer’s analysis ever
married women who gave birth before 20 had a higher
mortality risk at ages 50–85 than other parous women.
The possible effects of late childbearing on health and
mortality at older ages are more controversial. In the
study of English aristocrats referred to above, women
who gave birth after the age of 40 had better survival
after age 60 (Westendorp & Kirkwood, 1998); a number
of other studies have reported similar findings (Perls,
Alpert, & Fretts, 1997). This includes a recent study of
very old women and men in China in which childbearing
after age 35 or 40, particularly having several children
after these ages, was positively associated with both
good health and survival from ages 80–85 to very old
age (Yi & Vaupel, 2004). In contrast, a recent study
from the US reported associations between late child-
bearing (first birth after age 35) and a range of adverse
health indicators after the age of 50 including diabetes,
hypertension, congestive heart failure, poor dental
health, vision difficulties and impaired physical mobility
(Alonso, 2002). Consistent with this, a long-term follow
up of college women in the US found that women who
gave birth after the age of 40 had the highest mortality
risk (Cooper, Baird, Weinberg, Ephross, & Sandler,
2000).
One further aspect of fertility history which may be
associated with health in later life is birth spacing. In the
developing country context, it has been hypothesised
that closely spaced births may be associated with a risk
of maternal depletion and consequent poorer health,
although evidence on this is inconclusive (Menken et al.,
2003). Longer term implications of short birth intervals
have not, however, been examined.
Changes in fertility patterns in England and Wales
Improving our knowledge and understanding of
associations between fertility histories and health and
mortality in mid and later life is particularly important
in the current context of population ageing and
substantial changes in partnership and parenting his-
tories over the course of the 20th century in England and
Wales and elsewhere. Period total fertility rates (TFRs)
in England and Wales fell to a low point of 1.8 in the
second half of the 1930s before rising to a peak of 2.9 in
1964 and then falling again to a second low point in the
second half of the 1970s (OPCS, 1987). A slight
‘recovery’ in fertility in the early 1980s was followed
by a further fall and in 2001 the TFR fell to the lowest
level ever recorded (1.64). Viewed from a cohort
perspective, there have been large changes in the
proportions never-marrying, remaining childless and,
among parous women, in distribution by family size and
in timing of fertility. Thus some 15% of women born in
1900 were never-married by age 50 and results from the
ARTICLE IN PRESSE. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228220
1951 census suggest that as many as a third of women in
these very early twentieth century cohorts remained
childless (Werner, 1987; Grundy, 1996). Among those
born in 1935, by contrast, fewer than 5% were never-
married by age 50 and only 11% remained childless.
Changes in the timing of fertility have also been
substantial. Age specific fertility rates for women aged
40 and over exceeded those of teenagers, often
substantially, until the 1940s. By 1971, however, teenage
age specific fertility rates (51 births per 1000) were five
times higher than those of the 40 and over group (9 per
1000) (Werner, 1987). More recent cohorts show a
‘return’ both to later ages of childbearing and a high
prevalence of childlessness, but in the context of more
diverse, and disrupted, partnership arrangements.
Research questions
These historical changes mean that there are con-
siderable differences in the fertility histories of women
who are now of advanced age, in early old age or mid
life. The consequences of these variations for support in
old age are recognised to be important. In this paper we
investigate whether there are also consequences for
health status in later life, which is a major influence on
needs for support. We use data from a nationally
representative record linkage study from England and
Wales, the Office for National Statistics Longitudinal
Study (ONS LS) to analyse associations between fertility
history and an indicator of health status in mid or later
life and mortality after age 50 among women born
between 1911 and 1940. As reported above, this data set
was used by Doblhammer (2000) to investigate the
mortality of 56,000 ever-married women aged 40–59 in
1971 during the period 1971–1996. Our analysis extends
this work in several important ways. Firstly, we include
more adequate control for socio-economic characteris-
tics by using measures of housing tenure, car access and
occupationally based social class, as well as the
educational qualification indicator used in Doblham-
mer’s analysis (which is of very limited use as 92% of the
women in the cohorts considered in Doblhammer’s
analysis fell into the ‘basic’ qualification group); we also
control both for baseline marital status and for
subsequent widowhood. Secondly we include all women,
not just those who were ever-married in 1971 and so our
analysis of associations between nulliparity and later
health compares all nulliparous women with all parous
women, rather than just nulliparous ever-married
women with parous ever-married women. Thirdly, by
making use of linked birth data we extend the analysis to
all women born between 1911 and 1940 and alive in
1971; use of linked birth data also improves capture of
births after 40 among the earlier cohorts. Fourthly, we
examine the possible effect of short birth intervals on
later life mortality and health and analyse associations
between parity and mortality in greater detail, rather
than using aggregated categories. Thus we compare
women with 0, 1, 2, 3, 4, and 5 or more births, rather
than collapsing parous women into those with one or
two births and those with three or more. Fifthly, as well
as analysing associations between teenage and late
(439) childbearing, we also examine variations accord-
ing to age at first and last birth across the distribution.
Finally, we include presence of limiting long-standing
illness in 1991 as an outcome measure, as well as
mortality 1971–2000.
The specific research questions addressed are whether
early childbearing and closely spaced births are asso-
ciated with worse health outcomes in mid and later life,
even after control for socio-economic characteristics;
whether overall parity is associated with later life health
outcomes (again allowing for socio-economic character-
istics); whether late childbearing has positive or negative
associations with later health and mortality and whether
these effects vary between cohorts.
Data and methods
The ONS LS is a record linkage study of approxi-
mately 1% of the population initially based on those
enumerated in the 1971 Census of England and Wales
(approximately 500,000 people). Sample members were
traced in the National Health Services Central Register
(NHSCR) and record linkage used to add information
from subsequent censuses and from vital registration,
including births to sample mothers, death of spouse, and
death. The LS has been maintained through the addition
of 1% of new births and immigrants, but our analyses
here are based on follow up of women from the initial
1971 sample. We selected all women present in the 1971
census sample and then aged 31–59 (birth cohorts
1911–1940). In most of the analysis we have divided
these women into three groups born in 1911–1920,
1921–1930 and 1931–1940 respectively. These cohorts
were chosen as our interest is in possible associations
between fertility history and health and mortality in the
post reproductive period. We therefore wanted to
include only those we could observe for a reasonable
period after the age of 50. Women who were aged 60 or
over in 1971 (born before 1911) could not be included as
no fertility data were available for them.
The fertility history data come from a combination of
1971 Census and subsequent vital registration informa-
tion. The 1971 Census included questions on the marital
and fertility histories of ever-married women; subse-
quent linkage of births to sample mothers (of all marital
statuses) is currently complete to the end of 2000, as is
linkage of deaths of sample members and their spouses.
ARTICLE IN PRESS
Table 1
Parity distribution of women born in 1920 and women born in
1940: comparison of results from the LS sample and from
official statistics
Parity Birth cohort 1920 Birth cohort 1940
LS Official
statistics
LS Official
statistics
0 22 21 13 11
1 24 22 13 13
2 26 27 36 36
3 16 16 22 22
4+ 12 14 16 18
Sources: Official statistics from ONS (2002); ONS Longitudinal
Study, authors’ analysis.
E. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228 221
For the women included in this analysis we therefore
have near complete fertility histories to the end of the
reproductive period. There are, however, some sources
of potential omission. The first arises because in 1971
only ever-married women were asked to provide fertility
history data and they were only asked to record births
within marriage. We therefore have no data on non-
marital births prior to 1971. For cohorts born between
1920 and 1940, non-marital fertility generally accounted
for only 4–6% of all births in England and Wales, so the
effect of this omission is relatively slight (OPCS, 1987).
A second minor problem relating to the census data is
that a small proportion of ever-married women neither
entered dates of birth of children nor wrote ‘none’ on the
fertility section of the census form, as women without
children were instructed to do. We have assumed here
that these women were childless, an assumption
supported by post-enumeration quality checks on the
1971 Census which found that a quarter of childless
women left the fertility history section of the form blank
(Hattersley & Creeser, 1995). We additionally checked
the household data for these women to ensure they had
no children living with them and analysed their
characteristics and subsequent mortality, which we
found to be very similar to that of women definitely
known to be childless. The effect of this may be that we
slightly overestimate childlessness, but the proportions
involved are relatively small (2–4% of women in the
three birth cohorts we examine). Post 1971 fertility
information comes from linkage of births, both marital
and non-marital, and some births may have been missed
due to linkage failure, estimated to be around 8–9%
(Hattersley & Creeser, 1995). As a check on the validity
of the fertility history data, we compared the parity
distributions we derived for LS members born in 1920
and 1940 with official ONS figures derived from vital
registration for the whole population. As can be seen
(Table 1) this suggests a slight overestimation of
childlessness and underestimation of high parity in the
LS but an overall close correspondence. The slight
differences in proportions childless, especially for the
1940 cohort, probably reflects the fact that the LS data
do not capture non-marital births prior to 1971.
Linkage rates of deaths in the LS are better than for
births and it is estimated that only 1% of deaths are
missed (this difference partly reflects the fact that there
are two independent methods for linking deaths). In
addition to mortality, we use presence of limiting long-
standing illness, as reported in the 1991 Census, as an
outcome measure.
We excluded from the study women who were
identified as potential members of the LS from the
1971 Census but not traced in the NHSCR; known
emigrants; and those lost to follow up (not found in
subsequent censuses and with no event records—many
of these are thought to be emigrants). A few other cases
with discrepancies in dates or implausible ages at giving
birth (o11 or 454) were also excluded leaving a final
sample of 87,246 women. These exclusions amounted to
5.5% of the initial sample. We also had to exclude from
the mortality analyses the small proportions of women
resident in institutions in 1971 (o2%), as information
on relevant co-variates was not available for them. For
the same reason we excluded from the analysis of
variations in longstanding illness in 1991, 1.4% of
women who were then in institutions.
We used survival analysis to investigate the effects of
parity and spacing and timing of fertility on late-adult
mortality controlling for a range of relevant socio-
demographic and socio-economic characteristics in
1971. These co-variates were marital status (at 1971
but adjusted for subsequent widowhood); social class
based on own current or past occupation (manual, non-
manual, no occupation); housing tenure (owner occupier
versus tenant) and car access (household has use of car/
no use of car). We also included an indicator of
educational status. However, the 1971 Census only
collected information about qualifications equivalent to
or higher than ‘A’level’ (a school qualification gained at
around age 18) so this variable only distinguishes a small
minority of the population from the rest. The distribu-
tion of the three cohorts by these characteristics is
shown in Table 2 (the table also shows the proportion
excluded because of institutional residence). Those born
in 1911–1920 were aged 51–60 in 1971 whereas the
1931–1940 cohorts were only aged 31–40: variations in
the distributions reflect both these age differences (for
example, differences in the proportions who were
widows) and cohort differences (for example, the higher
proportion of women with an educational qualification
in later born cohorts).
Our analyses are restricted to women who survived to
age 50. Estimates from the Government Actuary’s
Department indicate that of girls born in 1911 who
survived to age 15, 9% died between their 15 and 50
ARTICLE IN PRESS
Table 2
Distribution of the sample by grouped birth cohort and 1971
characteristics included in the analysis
Characteristics in
1971
Birth cohort
1911–1920
(%)
1921–1930
(%)
1931–1940
(%)
Marital status
Single 9.1 7.2 6.9
Married 78.0 87.1 90.0
Divorced 2.1 2.2 2.3
Widow 10.8 3.5 0.9
‘A’level’+a,b 7.3 9.1 12.7
Non manual social
classb25.1 31.6 26.6
Manual social classb 33.3 30.7 23.8
Not workingb 41.5 37.7 49.5
Household has
access to carb55.5 66.2 69.2
Owner occupierb 50.1 51.7 58.3
In institution 1.7 1.0 1.1
N 30 599 30 442 26 436
Source: ONS Longitudinal Study, authors’ analysis.a‘A’level’; A’level equivalent, or higher qualification (quali-
fications gained at 18+).bNo information on these characteristics available for those
in institutions in 1971.
E. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228222
birthdays; equivalent proportions for the 1921 and 1941
cohorts were 7% and 4%. This means that if, for
example, high parity women had greater risks of dying
before 50 (which may particularly apply in the oldest
cohort) we may slightly underestimate risks associated
with high parity.
We firstly examined the risk of dying from age 50 until
the end of 2000 for the 1911–1920, 1921–1930 and
1931–1940 birth cohorts, separately. The length of
observation for each cohort varied, thus we observed
the earliest from age 50 to age 80–89 and the last only
from age 50 to age 60–69. Secondly we ran the analysis
with a pooled sample, with censorship at 31st December
2000 or at age 70 and an additional control for cohort
(as the three cohorts were aged 50–69 during different
periods in which mortality risks varied considerably).
The model specified is shown below
logit ðlitÞ ¼ aðtÞ þ b1X i1 þ b2X i2ðtÞ;
where t is survival time, measured in years, starting from
age 50, lit is the probability of death of a woman i in
year t, given that she was alive at year t�1, Xi1 are the
time constant covariates (socio-economic indicators at
1971 census, fertility measures) of the woman i, and b1their coefficients to be estimated, and Xi2 are the time-
varying covariates (widowhood) of the woman i, and b2their coefficients to be estimated.
We use discrete-time event-history models where the
year is the time unit because for confidentiality reasons
only year of birth, not day and month, is available for
analysis.
We additionally used logistic regression to model
probability of having a limiting long-term illness in
1991, for those who survived to 1991, controlling for
characteristics in 1991, and for changes in marital status,
car ownership and housing tenure between 1971 and
1991.
Results
Fertility characteristics and differentials in survival
In this section, we consider the fertility characteristics
of the cohorts of interest and, in order to assess any bias
arising from linkage failure and the other problems
referred to above, make some comparisons with results
from other sources. We then present the results of
survival analysis undertaken for each cohort separately
and then for a pooled cohort observed from ages 50–69.
Table 3 shows indicators of the fertility histories of the
three cohorts considered and also the odds ratios for
mortality by the fertility indicators for the three grouped
cohorts studied.
Looking first at the fertility characteristics of the three
cohorts considered, it can be seen that these vary very
considerably. The oldest cohort, born 1911–1920,
included a relatively high proportion who never married
or married but had no children (26%), and a high
proportion with only one child (23%) while only 15% of
the women born in 1931–1940 remained childless and
14% had one child only. Mean age at birth of the first
child decreased consistently across the three cohorts
from 26.8 to 24.7, as did mean age at birth of the last
child, from 32.1 to 30.1. The latest born cohort included
a much larger proportion of teenage mothers compared
with the earliest cohort, but only 3% of parous women
who had a child at age 40 or older, compared with 10%
of mothers born 1911–1920. Overall fertility increased in
successive cohorts as did the proportion who had at least
one intergenesic interval (interval between births) of 18
months or less. The proportion of women who had had
twins showed no cohort variation, which is reassuring as
we would not expect variation in this.
Our estimates of cohort TFR for the 1921–1930
cohorts combined is 1.9 and that for 1931–1940 is 2.2
whereas official estimates are 2.1 and 2.4 respectively
(Office for Population, Censuses & Surveys, 1987; ONS,
2002). It is harder to test the validity of results for
women born before 1920 as information on prior births
ARTIC
LEIN
PRES
S
Table 3
Distribution of women by fertility characteristics (at the end of the reproductive period) by grouped birth cohort, and results from the event history model for mortality after age 50
Birth cohort
1911–1920 1921–1930 1931–1940
Parity Sample (%) Adjusted OR (95% CI) Sample (%) Adjusted OR (95% CI) Sample % Adjusted OR (95% CI)
All women
0 26.0 1.13** (1.08–1.18) 20.7 1.22** (1.14–1.31) 15.0 1.28** (1.10–1.49)
1 23.0 1.06** (1.02–1.11) 19.8 1.04 (0.98–1.11) 13.7 1.10 (0.96–1.27)
2 (ref) 26.0 1.00 28.8 1.00 33.4 1.00
3 13.5 1.01 (0.96–1.06) 16.0 0.99 (0.93–1.07) 21.1 1.01 (0.89–1.15)
4 5.8 1.05 (0.98–1.12) 7.6 1.01 (0.92–1.11) 9.6 1.11 (0.95–1.30)
5+ 5.7 1.14** (1.06–1.22) 7.0 1.12* (1.02–1.22) 7.2 1.25** (1.06–1.46)
TFR 1.70 1.94 2.20
Number of deaths 18 495 8622 2212
Percentage of cohort dead
between age 50 and end 2000
60.4 28.3 8.4
N 30 599 30 442 26 436
Parous women
Had a child agedo20 4.4 1.15** (1.06–1.25) 4.7 1.16* (1.04–1.29) 7.5 1.30** (1.11–1.53)
Had a child aged439 10.2 0.93* (0.87–0.99) 7.9 0.89* (0.81–0.98) 3.1 0.94 (0.72–1.22)
Had an intergenesic intervalo18
months
11.6 1.19** (1.12–1.26) 15.2 1.01 (0.93–1.09) 19.2 1.08 (0.94–1.23)
Had twins 2.4 1.13* (1.01–1.27) 2.5 1.12 (0.97–1.31) 2.4 1.19 (0.90–1.56)
Mean age at first birth 26.8 (SD 5.0) 25.7 (SD 4.6) 24.7 (SD 4.3)
Mean age at last birth 32.1 (SD 5.5) 31.3 (SD 5.6) 30.1 (SD 4.7)
N 22 642 24 138 22 477
Results from fully adjusted models controlling for age, marital status, social class, education, car access and housing tenure (all in 1971) and widowhood post 1971, excluding women
in institutions in 1971 (but including those who later moved to an institution).
*Po0:05; **Po0:01:Source: ONS Longitudinal Study, authors’ analysis.
E.
Gru
nd
y,
C.
To
ma
ssini
/S
ocia
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cience
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edicin
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17
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223
ARTICLE IN PRESSE. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228224
was not collected via the birth registration system
until 1938 and retrospective data for these cohorts
have not been collected in the national survey used to
produce official estimates (the General Household
Survey). However the results found here are consistent
with earlier estimates made by Grundy (1996) on the
basis of the 1951 Census, although the proportion
childless appears slightly higher than expected and the
overall level of fertility, as in the later cohorts, slightly
too low. These slight differences probably reflect
exclusion of a few pre 1971 non-marital births and the
known slight incompleteness of linkage of births after
1971.
In the analysis of associations between fertility
characteristics and mortality risk, we present odds ratios
of death by the characteristics of interest from models
including the socio-demographic control variables
discussed earlier. Odds ratios for these control variables
are not shown, in the interests of simplifying the
presentation, but are available from the authors on
request.
The upper section of Table 3 shows the results
obtained in the model run on all women, while the
lower presents results from analyses of the mortality of
parous women. In all three cohorts childless women and
women with five or more children have consistently
higher risks of mortality than women with two children,
even after controlling for other demographic and socio-
economic factors. Risks for mothers of three children
were identical to those of mothers of two and risks for
mothers of four children were only raised in the
youngest cohort (and not significantly so). In the
1911–1920 cohort there is additionally a significant
excess risk for those who had only one child (odds ratios
for mothers of one child only were also raised in the later
cohorts, but did not reach conventional levels of
statistical significance).
The lower part of Table 3 includes the results of the
survival analysis run on parous women. Having a child
before age 20 was consistently associated with a higher
mortality risk and having a child after age 40 was
significantly associated with lower mortality for the
cohorts born between 1911 and 1930. The reference
category in both these cases is a wide one—women aged
20–39. We investigated effects of age at childbearing in
more detail by analyzing variations in mortality risks by
age group at first and age group at last birth, using 10
year age groups. These results, not shown here but
available from the authors, showed that those who
became mothers before 20 had a higher mortality risk
than women who had their first birth in their 30s, but
there was no difference between 20 and 29 year old first
time mothers and those aged 30–39 or 40 or more.
Results for age at last birth showed, again consistent
with results for all births, an advantage for mothers
whose last birth was at age 40 or over. Additionally,
among women born between 1911 and 1930, those who
had their last child in their 30s had a slightly lower
mortality risk than those who completed their child-
bearing before the age of 30.
Among women born 1911–1920, having a multiple
birth or other short birth interval was also associated
with higher mortality. The smaller number of deaths
among later born women means that fewer results are
likely to be statistically significant.
Fig. 1 shows the results from the pooled model of
mortality between age 50 and 69 for all three cohorts. As
in the cohort specific analysis, nulliparity, high parity
and early childbearing were associated with increased
risks, as were having one child only, having a multiple
birth or having a short birth interval. There were of
course also large differences between the cohorts in
mortality risk in the age groups considered reflecting the
substantial improvements in mortality over the period.
We had hypothesised that the effects of the fertility
parameters considered might vary between the cohorts
as a result of, for example, differences in selective
factors, such as differences in chances of getting married,
and period differences in antenatal and obstetric care.
We accordingly fitted various interaction terms, but as
none were statistically significant these were not
included in the final model.
Health status in 1991
The 1991 Census included a question on presence of
limiting longstanding illness and in the final part of our
analysis we used a logistic regression model to examine
associations between fertility characteristics and this
outcome. Women included in this model had to have
survived to 1991 and of course different birth cohorts
were at different ages, ranging from 51 to 80, at this
date. We also had to exclude those in institutions in 1991
as information on co-variates was lacking for this group.
Those excluded because of institutional residence
accounted for 4.2% of those born 1911–1920, 3.1% of
those born 1921–1930 and 2.4% of those born
1931–1940. In addition to the socio-economic variables
in 1971 Census, we also controlled for changes in the
period 1971–1991 in marital status, in tenure type and
car access (e.g. if a woman changed from being married
to unmarried or from being a owner to being a renter).
Results, presented in Table 4, show that in all three
cohorts, having had five or more children was associated
with a higher risk of long term illness in 1991, as was
having had a teenage birth. In the youngest cohort born
1931–1940 and aged 51–60 in 1991, nulliparity was also
a risk factor. Among parous women, having had a short
birth interval was positively associated with long term
illness, and having had a child at age 40 or later was
associated with reduced risk.
ARTICLE IN PRESS
Spacing < 18 months
Child after 40
Had twin
Child before 20
Parity 5
Parity 4
Parity 3
Parity 2
Parity 1
Parity 0
OD
DS
RA
TIO
S an
d 95
% C
I
1.4
1.2
1.0
0.8
Fig. 1. Odds ratios and 95% confidence intervals, from the event history model for mortality between ages 50 and 70, pooled cohorts.
Controlling for age, marital status, cohort, social class, education, car access, housing tenure (all in 1971), and period, excluding
women in institutions in 1971 (but including those who moved to an institution subsequently).
E. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228 225
Discussion
This analysis of data from a large nationally
representative study of women in England and Wales
lends support to hypotheses of links between fertility
histories and health in mid and later life. In analyses
including controls for indicators of socio-economic
position and socio-demographic status, we found higher
risks of adverse outcomes among nulliparous than
parous women; higher risks associated with high parity
and closely spaced births; and associations between
teenage childbearing and childbearing at age 40 or more
with health and mortality in later life.
In all the cohorts we considered, nulliparity was
associated with higher risks of mortality. This is
consistent with results from a number of studies, but
not with those of some historical studies which have
suggested lower mortality among the nulliparous. It is
possible that we have slightly overestimated the effect of
nulliparity, as some women who had a non-marital birth
prior to 1971, a group likely to have ‘risky’ lifestyles,
may have been misclassified as nulliparous. However,
this bias should be relatively small, because as, noted
earlier, non-marital childbearing was low in the period
considered, and because to be misclassified as nullipar-
ous, such mothers would have had to have had no
subsequent children in marriage (or outside of marriage
post 1971). The greatest excess risk was observed in the
youngest cohort, which included the lowest proportion
of nulliparous women, and it was only in this group that
nulliparity was associated with higher odds of reporting
limiting long-term illness. This is consistent with the idea
that selection effects may partly account for the higher
risk, as the nulliparous will include those with health
problems which make marriage or motherhood less
likely and women with these characteristics may account
for more of the nulliparous group in cohorts in which
nulliparity is rarer. However, other factors are likely to
be important as well. These include higher risks of
specific diseases, notably breast cancer; an effect we will
examine in later cause-specific analyses, and lack of
social support from children.
Poorer outcomes were also observed for women with
one child only, although in the case of mortality this was
only significant in the oldest cohort and in the case of
long-standing illness, only in the middle cohort. Again
selection effects may be important, as those with one
child only will include women with health problems,
including problems related to first pregnancy, which
prevented or discouraged them from having more
ARTICLE IN PRESS
Table 4
Odds ratios from logistic regression model of presence of limiting long term illness in 1991
Birth cohort
1911–1920 (aged 71–80 in 1991) 1921–1930 (aged 61–70 in 1991) 1931–1940 (aged 51–60 in 1991)
OR 95% Wald CI OR 95% Wald CI OR 95% Wald CI
All women
0 0.96 (0.88–1.05) 1.04 (0.95–1.14) 1.18** (1.04–1.33)
1 1.04 (0.96–1.13) 1.10* (1.01–1.20) 1.04 (0.92–1.17)
2 (ref) 1.00 — 1.00 — 1.00 —
3 1.04 (0.94–1.15) 1.04 (0.95–1.13) 0.99 (0.89–1.10)
4 1.12 (0.98–1.29) 1.00 (0.88–1.12) 1.10 (0.97–1.25)
5+ 1.26** (1.10–1.44) 1.22** (1.08–1.37) 1.33 (1.16–1.52)
Percentage with
long-term illness
39.1 25.6 16.3
N 19 095 24 977 24 233
Parous women
Had a birth
agedo20
1.30** (1.10–1.55) 1.37** (1.18–1.59) 1.41** (1.23–1.61)
Had a birth
aged439
0.93 (0.83–1.05) 1.02 (0.91–1.16) 0.65** (0.51–0.82)
Had an
intergenesic
interval o18
months
1.04 (0.92–1.18) 1.08 (0.98–1.20) 1.15** (1.03–1.29)
Had twins 0.90 (0.71–1.13) 1.14 (0.93–1.40) 0.92 (0.71–1.19)
Controlling for age, marital status, social class, education, car access and housing tenure (in 1991) and changes in marital status, car
and home ownership in the period 1971–1991.
*Po0:05; **Po0:01:Source: ONS Longitudinal Study, authors’ analysis.
E. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228226
children. Lower levels of social support may also be a
factor for those with one child only, as well as the
childless. Mothers who have only one child, for example,
are less likely to see a child at least once a week than
mothers with two or more children (Tomassini et al., in
press).
We found that women with three births had no
greater risk of mortality or longstanding illness than
mothers of two children, and there was no statistically
significant difference between mothers of four children
compared with mothers of two. However women with
parities of five or more had consistently elevated
mortality risks and higher odds of reporting limiting
long term illness in 1991. This suggests a ‘threshold’
rather than an additive effect and demonstrates the
importance of disaggregating parity as far as possible.
We also found risks of higher mortality, and in the
earliest cohort, of poor health, associated with having
twins and short birth intervals. A large literature on
links between fertility and maternal health in less
developed countries has considered adverse conse-
quences of short birth intervals for mothers as well as
children, but not definitively shown it for the former,
and this issue has been rarely examined in developed
countries. The associations between high parity and
closely spaced births (including twins) and later health is
consistent with the hypothesis of maternal strain, both
physical and psychological, arising from the stresses of
pregnancy and childrearing, especially rearing of more
than one young child at once.
Our results also indicate long-term health effects of
teenage childbearing. Odds ratios for mortality after age
50 among teenage mothers were 1.15 (1.06–1.25) in the
1911–1920 birth cohort, 1.16 (1.04–1.29) in the
1921–1930 cohort and 1.30 (1.11–1.53) in the youngest
cohort born 1931–1940. Excess risk of mortality for the
two earlier cohorts is less marked than in Doblhammer’s
analysis (1.26 for those born 1911–1920) because we
include greater control for confounding socio-economic
factors. Women who had a child before twenty and who
survived to 1991 also had 30–40% higher odds of then
reporting limiting long-standing illness. It is interesting
that in our analysis the effects of teenage childbearing
appear as great, or indeed greater, in the youngest
cohort as in the earlier ones even though teenage
mothers were relatively most numerous, and therefore
less ‘selected’ in this later cohort. We also would have
expected to find larger effects in the earlier cohorts
ARTICLE IN PRESSE. Grundy, C. Tomassini / Social Science & Medicine 61 (2005) 217–228 227
because one pathway from teenage childbearing to
poorer later health may be through physiological effects
particularly affecting poorly nourished young women or
women who had not completed their own physical
growth. We would have expected such influences to be
most important in the oldest cohort who, as a group,
would have experienced more hardship in childhood and
young adulthood and later physical maturation than
later born women.
Our results generally support those studies which have
reported a negative association between late child-
bearing and both mortality and poor health—most of
which have been undertaken on either historical
populations or in contemporary less developed popula-
tions—in contrast to the results reported from con-
temporary US populations. Selection effects are likely to
be an important explanation for this association. A
precondition of late childbearing is continuing physio-
logical ability to become pregnant and carry a baby to
term. Although permanent cessation of menses generally
occurs in the late 40 s or early 50 s, fecundity (ability to
bear a child) starts to decrease well before actual
menopause (Rahman & Menken, 1993). Smoking is a
risk factor for earlier menopause and earlier menopause
is associated with higher subsequent mortality (McKin-
ley, Bifano, & McKinley, 1985). However, feeling
physically well and ‘young’ enough for motherhood at
40 plus is probably a more important influence than the
constraining one of continuing fecundity, especially in
the youngest cohort considered who would have had
access to modern contraceptive methods and legal
abortion. Differentials in social support may also be
important. The late born children of mothers in the
youngest cohort would for the most part still have been
at home in 1991 and for at least part of the mortality
follow-up period. As having multiple roles appears to be
positively associated with health in mid life women, this
in itself may have had a positive influence on health
(Hibbard & Pope, 1991; Adelman, 1994). Interestingly
we again found little evidence of differences between the
cohorts we considered in the direction of these associa-
tions, even allowing for interactions, despite large
differences in the fertility characteristics of these
cohorts. Overall the consistency of associations in all
the cohorts considered suggests that biological factors
may play an important part in associations between
childbearing histories and health in mid and later life.
As already noted, there are some limitations to our
analysis. Firstly it is probable that between 5% and 10%
of births were not captured either through omission of
pre 1971 non-marital births or linkage failures in the
post 1971 period. Secondly, we have no information on
childhood characteristics and indeed only socio-eco-
nomic and socio-demographic information for points of
time well into adulthood. Additionally, we have no data
on physical measures of health or on psychological
characteristics which may be associated with both
fertility and health trajectories. In particular early
motherhood, which here appears to have long lasting
negative effects on health, may be associated with
characteristics and behaviours, including smoking,
which we have been unable to control for. This points
to the need for analyses including detailed information
on antecedent characteristics and we are now engaged in
collaborative work using data from the British 1946
birth cohort study in order to investigate this further.
Despite these caveats, we believe our results lend
powerful support to arguments that personal demo-
graphic history is an important factor to be considered
in analyses of health and mortality variations in later life
and, more particularly, that differing fertility histories
may have long reaching consequences.
Acknowledgements
The work reported here was supported by the
Economic and Social Research Council, UK, Grant
Reference Res-000-0394. We are grateful to the Office
for National Statistics for access to data from the ONS
Longitudinal Study; the project was approved by the
Longitudinal Study Research Board.
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