fertility history and later life health: is the association mediated or moderated by physical...
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Fertility history and later life health: is the association mediated or moderated by
physical activity ?
Emily Grundy and Sanna Read
http://pathways.lshtm.ac.uk pathways@lshtm.ac.uk
@PathwaysNCRM
Physical activity, parenthoodhistories and health in later life
• Early parenthood, high parity and nulliparity are associated with worse later life health in women and men in England and various other countries
• This association may reflect several direct and indirect mechanisms • Health related behaviours such as physical activity may mediate the
association, or moderate effects• It is also important to take into account other health related behaviours such
as smoking, and socioeconomic position and social support.
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Physical activity, parenthoodhistories and health in later life
How does physical activity promote health and physical functioning ?– improved body composition – healthy lipid levels– glucose homeostasis and insulin sensitivity– blood circulation– reduced blood pressure and inflammation
How might fertility history influence physical activity ?– parents more likely to adopt health promoting behaviours than childless;
activities with children may involve participation in physical activities – and this may be carried forward into post childrearing phase of life
– however, some types of fertility trajectory (early parenthood and large family size) may be assocaited with a less healthy lifestyle
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Physical activity, parenthoodhistories and health in later life
• Does physical activity moderate the health risks related to parity and early birth ?– Previous research shows that in new mothers physical activity reduces
post- pregnancy overweight – Whether or not physical activity moderates the association between
fertility history and later life health not previously investigated
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Aim
• To investigate whether physical activity mediates or moderates the association between fertility histories and later life health in older men and women.
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Parenthood history
Health
Demographic and life history factors
Is the association between parenthood history and health mediated by physical activity?
The mediation model to be tested
Physical activity
Parenthood history
Health
Demographic and life history factors
Is the association between parenthood history and health mediated by physical activity?
The mediation model to be tested
Physical activity
Parenthood history
Functional limitations
(initial level and rate of change)
Demographic and life history factors
Does physical activity moderate the association between parenthood history and health?
The moderation model to be tested
Physical activity
Data
• English Longitudinal Study of Ageing (ELSA) waves 1 - 5 (2002-2010) - nationally representative survey of men and women aged 50+ (mean age = 63, SD = 9.2 in wave 1)
• Socio-demographic information and self reported health collected in all waves
• Detailed health data including biomarkers collected in alternate waves –biomarker data used to derive an index of allostatic load
• Retrospective life course data collected in wave 3. Analysis based on those providing life course data (n = 6207)
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MeasuresDemographic & life course:
Age, education, childhood health problem (retrospective), married/not married, and co-residence with child (time varying); ever divorced, ever widowed (wave 3).
Parenthood history: Number of natural children (0, 1,2,3,4+); any step child; any adopted child; deceased child; for parents: young (<20/23) age first birth; late age last birth (>34/39).
Intermediate measures: Physical activity; wealth; smoking; social support and strain (Wave 1)
Health outcomes: Allostatic load (wave 2); limiting long-term illness (wave 3); functional limitations (waves 1-5).
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Allostatic load scores in ELSA• Allostatic load: multisystem physical dysregulation resulting from long-term exposure to stress• Grouped allostatic load index: number of biomakers indicating high risk (upper 25th percentile,
except for peak expiratory flow lower 25th percentile) calculated separately for men and women (and age group), weighted by the number of markers per system and adjusted for medication
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System Biomarker
Cardiovascular Systolic blood pressure
Diastolic blood pressure
Inflammation Fibrinogen
C-reactive protein
Lipid metabolism Triglycerides
Glycosylated haemoglobin
Total/HDL cholesterol ratio
Body fat Waist/hip ratio
Respiratory Peak expiratory flow
Associations between fertility & parenthood variables, allostatic load and health limitation among men and women in ELSA
Allostatic load Health limitation
No. Natural children (ref = 2) Men Women Men Women
0 -0.05 0.04 0.10 0.18
1 0.04 -0.14 0.14 0.07
3 0.01 0.18 0.07 -0.01
4+ 0.34* 0.29* 0.29* 0.23*
Early child birtha 0.51*** 0.58*** 0.46*** 0.43**
Late childbirtha 0.10 -0.16 0.29* -0.23*
Adopted child -0.15 0.55** -0.24 0.09
Step child 0.08 0.03 0.30* -0.09
Child died 0.22 0.03 0.21 0.19
Models include health in childhood; age; education; married/not married; ever widowed; ever divorced; intergenerational contact. Allostatic load adjusted for fasting & inhaler use. a parents only.
Associations between parity and physical activity in ELSA
0 1 2 3 4+0%
20%
40%
60%
80%
100%
Sedentary or mild Moderate at least once a week
Vigorous at least once a week
0 1 2 3 4+0%
20%
40%
60%
80%
100%
Men
Women
Number of children
Physical activity
Associations between early parenthood and physical activity in ELSA
No early childbirth Early childbirth0%
20%
40%
60%
80%
100%
Sedentary or mildModerate at least once a weekVigorous at least once a week
Physical activity
Men Women
No early childbirth Early childbirth0%
20%
40%
60%
80%
100%
Sedentary or mildModerate at least once a weekVigorous at least once a week
Physical activity
Adopted child
Wealth
Wave 1 Wave 2 Wave 3
Allostatic load
Limiting long-term illness
Children4 vs. 2
Smoking
Social strain
-0.45 (0.167)
-0.15 (0.025)
0.10 (0.021)
0.47 (0.09)0.71 (0.153)
0.12 (0.037) 0.28 (0.084)
Figure 1. Path model for all women in ELSA. Model adjusted for age, education, being married, ever divorced, ever widowed and childhood health. Significant paths are shown (unstandardized estimate and standard error). Source: Analysis of ELSA waves 1-3.
-0.58 (0.078)
Physical activity
-0.38 (0.040)
-0.61 (0.046)
-0.10 (0.028)
-0.19 (0.053)
Wealth
Wave 1 Wave 2 Wave 3
Allostatic load
Limiting long-term illness
Children4 vs. 2
-0.74 (0.092)
-0.13 (0.030)
-0.35 (0.048)
0.12 (0.023)-0.32 (0.069)
Figure 2. Path model for all men . Model adjusted for age, education, being married, ever divorced, ever widowed and childhood health. Significant paths are shown (unstandardized estimate and standard error). Source: Analysis of ELSA waves 1-3.
Smoking
Social strain
Physical activity
0.93 (0.174)
0.11 (0.037)
0.62 (0.099)
0.24 (0.086)
0.39 (0.097)
-0.63 (0.053)
-0.13 (0.027)
Wealth
Wave 1 Wave 2 Wave 3
Allostatic load
Limiting long-term illness
Early childbirth
Physical activity
Smoking
-0.52 (0.088) -0.14 (0.030)
0.09 (0.024)
-0.40 (0.049)
-0.39 (0.075)
0.48 (0.156)
-0.63 (0.055)
0.50 (0.109)
Figure 3. Path model for biological mothers. Model adjusted for age, education, being married, ever divorced, ever widowed ,childhood health, and coresidence with child. Significant paths are shown (unstandardized estimate and standard error). Source: Analysis of ELSA waves 1-3.
-0.24 (0.059)
0.38 (0.147)
-0.09 (0.034)
Wealth
Wave 1 Wave 2 Wave 3
Allostatic load
Limiting long-term illness
Early childbirth
Smoking
-0.43 (0.093) -0.15 (0.033)
0.12 (0.027)
0.41 (0.131)
-0.14 (0.056)
Figure 4. Path model for biological fathers. Model adjusted for age, education, being married, ever divorced, ever widowed, childhood health, and coresidence with child. Significant paths are shown (unstandardized estimate and standard error).Source: Analysis of ELSA waves 1-3.
-0.38 (0.066)
0.30 (0.149)
Physical activity
0.36 (0.164)
0.79 (0.132)
-0.10 (0.036)
-0.64 (0.066)
T1 T2 T3 T4 T50
0.5
1
1.5
2
2.5
3
Less than vigorous activity + 0 childrenLess than vigorous activity + 1 childLess than vigorous activity + 2 children Less than vigorous activity + 3 childrenLess than vigorous activity + 4 or more childrenVigorous activity + 0 childrenVigorous activity + 1 childVigorous activity + 2 children Vigorous activity + 3 children Vigorous activity + 4 or more childrenEs
timat
ed le
vel o
f fun
ction
al li
mita
tions
Men
T1 T2 T3 T4 T50
0.5
1
1.5
2
2.5
3
Less than vigorous activity + 0 childrenLess than vigorous activity + 1 childLess than vigorous activity + 2 children Less than vigorous activity + 3 childrenLess than vigorous activity + 4 or more childrenVigorous activity + 0 childrenVigorous activity + 1 childVigorous activity + 2 children Vigorous activity + 3 children Vigorous activity + 4 or more childrenEs
timat
ed le
vel o
f fun
ction
al li
mita
tions
Women
T1 T2 T3 T4 T50
0.5
1
1.5
2
2.5
3
3.5
Less than vigorous activity + early childbirthLess than vigorous activity + no early childbirthVigorous activity + early childbithVigorous activity + no early childbirth
Estim
ated
leve
l of f
uncti
onal
lim
itatio
nsMen
T1 T2 T3 T4 T50
0.5
1
1.5
2
2.5
3
3.5
Less than vigorous activity + early childbirthLess than vigorous activity + no early childbirthVigorous activity + early childbithVigorous activity + no early childbirth
Estim
ated
leve
l of f
uncti
onal
lim
itatio
nsWomen
Conclusions & Discussion
• Physical activity mediates the association between high parity and later life health. It also partially mediates the association between early parenthood and later life health.
• Mediation through physical activity is not as strong as through wealth.
• Physical activity moderates the levels of health disadvantage related to high parity and early childbirth
• Low parity (nulliparity, having 1 child compared to 2 children) was not associated with lower levels of physical activity or poorer health
• Important to investigate early life pathways to particular fertility trajectories- especially childhood SES and broader environmental influences (e.g. support from the state)
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Sample derivation and data availability
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WAVE 1
Core sample members n = 11392 Interview items available n = 10133
WAVE 2
Core sample members n = 8781
Interview items available n = 8779
Nurse visit: allostatic load score available n = 6187
All items available waves 1, 2 and 3
n = 4378
WAVE 3
Core sample members n = 7535
Interview items available n = 7191
Life history: fertility history available n = 6207
Allostatic load: 25th percentile high risk cut-off points, ELSA in wave 2 (2002).
Men Women
Aged 51-65 Aged 65+ Aged 51-65 Aged 65+
Inflammation (n = 1008-1017) (n = 982-986) (n = 1219-1232) (n = 1190-1196)
C-reactive protein >2.9 >3.4 >3.4 >3.9
Fibrinogen >3.4 >3.7 >3.5 >3.8
Cardiovascular (n = 1074) (n = 1106) (n = 1319) (n = 1398)
Systolic blood pressure >143 >149 >140 >151
Diastolic blood pressure >85 >80 >83 >79
Lipid metabolism (n = 1001-1017) (n = 965-983) (n = 1219-1233) (n = 1187-1196)
HDL/Total cholesterol ratio >5.0 >4.6 >4.4 >4.5
Triglycerides >2.5 >2.2 >2.1 >2.1
Glycosylated haemoglobin >5.7 >5.9 >5.6 >5.8
Body fat (n = 1216) (n = 1231) (n = 1486) (n = 1527)
Waist/hip ratio >1.00 >1.00 >0.88 >0.89
Respiratory (n = 1197) (n = 1190) (n = 1415) (n = 1437)
Peak expiratory flow <506 <406 <344 <265
No qualifica
tion
Marr
ied
Ever d
ivorce
d
Ever w
idowed
Long-t
erm healt
h problem in
child
hood0
102030405060708090
Distribution of the sample by demographic & life history variables
MenWomen
%
Coresident with child
Weekly contact
with child
Has adopted child
Has step child Has a child who died
0
5
10
15
20
25
30
35
40
45
50
Distribution of the sample by demographic & life history variables
MenWomen
%
0 1 2 3 4+ Early childbirth
Late childbirth
0
5
10
15
20
25
30
35
40
45
Distribution of the sample by demographic & life history variables
MenWomen
%
Number of children
<0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8-1.00
5
10
15
20
25
30
35
40
Distribution of the health outcomes
MenWomen
%
Allostatic load weighted means scoreHealth limitation
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