1. Poverty during the early years:
What have we learned
from the Quebec birth cohort?
Louise Séguin, MD, MPH, FRCPC
Department of Social and Preventive Medicine
Université de Montréal
Presentation at the University of Warwick.
April 2010

2. The presentation Impact of poverty on children’s health
Methodology aspects of the QLSCD
Poverty and health indicators
Some results
Trajectories of poverty from birth up to 8 years old
Analysis from 3 ½ years old to 6 years old
Analysis between 5 and 7 years old
What have we learned?

3. Child Poverty and Health
Links between child poverty and child health are well known;
New interest in studying the relationship between SES/poverty and health;
Dynamics of child poverty across time in relationship with child health outcomes are less well known:
Few data on poverty and physical health of children across the early childhood years
Few data on the mechanisms of this relationship in industrialized countries

4. Duration/timing of poverty and child health
Long term or chronic poverty has more impact on a child health than transitory poverty (Spencer, 2000; Séguin et al, 2005, 2007)
Some authors demonstrated that if a child grew up in a low SES family during his/her first 2 years of life, that child was more likely to experience a chronic illness at 10-11years old. (Chen et al, 2008)

5. Child Poverty and Adult Health
An adult who experienced early childhood poverty has a higher risk of:
Early mortality (Kuh, 2002; Claussen, Galobardes, 2008)
Cardiovascular diseases (Barker, 1992; Barker, 2001)
Type 2 diabetes (Lawlor, 2002)
Cognitive development problems (Richards, 2002; Yeung, 2002; Cheung, 2001; Guo, 2000)
Older age cognitive problems (Stern, 1994; Abbott, 1998; Kaplan, 2001)

6. Child Poverty and Adult Health
Child poverty during early childhood not only affects child health, it also jeopardizes future adult health independently of adult socioeconomic status
However we don’t know when such an impact begins in the course of a child’s life and what are the underlying mechanisms

7. Child poverty and adult health

8. Child poverty in Canada
Children are the age group most often affected by poverty in Canada.
Canada has higher child poverty rate than most Europeans countries

9. Child Poverty in Industrialized Countries – UNICEF 2007

10. Objectives of our study
To examine how timing and different durations of exposure to poverty and its associated adverse circumstances are related to the likelihood of experiencing childhood physical health problems
To examine which aspects of such adverse circumstances are more influential in this relationship

11. Defining poverty and SES
Absolute or relative lack of material resources
Low income
Socio-economic status (SES) :
Social position, social status
Composite indicator including 2 or more of the following indicators, sometimes only one:
Level of education, level of income, marital status, occupational status, neighborhood of residency.

12. SES/poverty and health: different views
The threshold or the SES gradient
The neo-materialist hypothesis:
lack of access to resources (food, housing, educational, recreational, etc)
exposure to a more noxious environment
The psychosocial hypothesis
self-perception of social status, or of position on the social ladder

13. The threshold or the gradient
Our choice is to look at the threshold effect (poverty) before examining the SES gradient effect
Most often there is a larger health gradient between the lowest SES class and the next one than between the other SES classes
“The steepest drop in mortality occurs as income increases at the bottom of income distribution”, (Nancy Adler, Ann. N.Y. Acad. SC., 2010)

14. Poverty
Poverty is not only about a lack of money or insufficient income
Lack of money/insufficient income determines and limits choices of resources: housing, food, etc
Living in poverty conditions involves being exposed to multiple adversities
Being poor is also associated with a perception of not having the possibility of functioning like the majority of people in one’s community

15. The Quebec Longitudinal Study of Child Development (QLSCD): the sample
Sampling from the Quebec live births records
By the Direction Santé Québec of the Quebec Institute of Statistics.
A representative cohort of 2120 singleton live births in in Quebec excluding those
residing in the Northern Quebec, Cree, and Inuit territories, and on Indian reserves
for whom duration of gestation is unknown
with a gestational age <24 wks or >42 wks

16. The QLSCD: general objective
The first objective of the QLSCD is to examine the determinants of school success. Therefore the data collection is oriented toward children developmental and behavioural variables and their family context.

17. The Quebec Longitudinal Study of Child Development (QLSCD): data sources
Data were collected annually at home by interviewers. Mothers were respondents in 97-99% of cases
Mothers and fathers also completed self-administered questionnaires
Birth data were extracted from hospital charts.
Health conditions at birth (birth weight, gestational age, congenital malformations....)

18. Participation rates in the QLSCD
Annual follow-up of 2120 children who were 5 months old in 1998 (initial participation rate: 83%)
Participation rate at follow-ups:
1 yr ½ : 96 % n= 2045
2 yrs ½ : 94 % n= 1997
3 yrs ½ : 92 % n= 1950
4 yrs : 92 % n= 1944
5 yrs : 83 % n= 1759
6 yrs : 70.4% n= 1492
7 yrs : 75.9% n= 1528
8 yrs : 68.4% n= 1451

19. Differential attrition
Those who are lost to follow-up are most often those with a low income, a lower level of education, who are lone parents or immigrants
Not anymore a representative cohort even if we use weighting to compensate for the losses.

20. Measures of poverty Poverty was defined in our study as
1-having a household income before taxes during the previous 12 months below the Low-Income Cut Offs (LICO) from Statistics Canada;
2- having a high score of lack of money for basic needs
Food, rent/mortgage, electricity, heating, prescribed drugs, clothing, others.

21. Measurement issues: defining poverty
Definition of the low-income cut-offs (LICO) by Statistic Canada:
A family is said to be under the LICO if they attribute 20% more of their income than the average Canadian family to food, shelter, and clothing.
The low income cut-offs (LICO) from Statistic Canada take into account:
Number of persons in the household
Number of people in the area of residency

22. Health indicators in the QLSCD: reported by the mother except for weight and height
Infections: respiratory, otitis, gastro-enteritis, others
Asthma diagnosis: age at diagnosis
Asthma attack: presence and number of attacks
Growth: growth delay, BMI, overweight, obesity
Injuries: presence, nature, location, cause
Emergency services: utilisation, reasons
Hospitalisation: at least one night, frequency, reasons
Maternal perception of the child’s health: excellent, very good, good, not too good, bad.

23. Biomarkers at 10 years old
Blood samples:
Glucose, insulin, lipids
Saliva samples from mother and child (one sample when awakening and one sample 30 minutes later on two different week days):
Cortisol awakening response or CAR
Holter data:
Cardiac rhythm during the interview and during blood sampling: cardiac rhythm variability
Blood pressure:
5 automatic measures with a programmed instrument

24. Child poverty and health : a complex relationship
Our results show that the relationship between child poverty and child health is not always linear;
There is usually a lag between exposure to poverty and its impact on health;
An accumulated (chronic) exposure has more effect on child health than a transitory one. Therefore we can observe different results from a longitudinal analysis than from a cross-sectional ones;
In this relationship, interactions were observed between mothers’ characteristics and child health.

25. Rate and duration of poverty among participants during their early years. QLSCD
Poverty rate at 6 years old: 16.6%
Duration of poverty < 4 years :
Never poor: %
Poor 1-2 episodes: %
Poor 3 episodes or +: 13.5%

26. Poverty trajectories- from birth to 8-years old

27. Maternal characteristics at the start of each poverty trajectory
Trajectories for insufficient income from birth
Stable lowest risk
Decreasing
risk
Increasing
Stable highest risk N
Col %
Age
<20 yrs 9
1.0 7
7.0 1 12
13.6
20-34 yrs
755
85.1 82
82.0 93
89.4 64
72.7
>=35 yrs
123
13.9 11
11.0 10
9.6
Living with a partner at birth
Yes
877
98.9 84
84.0
100
97.1 61
70.1 No
1.1 16
16.0 3
2.9 26
29.9
Education Level
College or university
684
77.1 47
47.0 37
35.6 34
38.6
High school/vocational
146
16.5 25
25.0 43
41.3 20
22.7
< High school 57
6.4 28
28.0 24
23.1
Immigration status
Non immigrant/Immigrant from Europe
862
97.2 88
88.0
96.2 74
84.1
Immigrant from non-Europ. Country
2.8
12.0 4
3.8 14
15.9

28. Health problems at 6 years old according to duration of poverty from birth to 4 years old. QLSCD
Never
poor
Poor
1-2 epis.
3-4 epis.
Maternal perception of child health <very good
6.3%
14.1%
19.4%
Asthma diagnosis
15.9%
23.9%
24.1%
Frequency of asthma attacks (3 or +)
1.9%
2.9%
4.2%
Emergency room utilisation
34.8%
43.4%
30.9%
Injuries
10.9%
13.7%
9.4%

29. Comparisons UK-Quebec
UKMCS
QLSCD %
Count
Health status
Ever had asthma attack
11.6
1688
13.6
258
Longstanding illness at 3-years old
15.8
2300
18.1
341
Limiting longstanding illness at 3-years old
2.9
422
1.6 31
Poverty status
SW1/IS2 in the child's 1st year of life
Yes
13.5
1965
11.0
209
Cumulative poverty
Never been in receipt of SW1/IS2
82.8
12052
86.5
1636
SW1/IS2 only in 1st year of life
4.4
640
5.9
111
SW1/IS2 only in 4th year of life
3.7
538
2.4 46
SW1/IS2 in both 1st & 4th years of life
9.1
1326
5.2 98
1-SW: Social Welfare; 2-IS: Income support

30. Risk of Chronic Illness Among Children Aged 3 to 3
Risk of Chronic Illness Among Children Aged 3 to 3.5 Years of the UKMCS and the QLSCD Birth Cohorts. Nikiéma, Spencer, Séguin, Pediatrics, Febr 2010
Models by Outcome
UKMCS
QLSCD
OR (95% C I)
SW1/IS2in the 1st year of life exclusively †
Asthma attacks
1.67 (1.39, 2.02)
1.52 (0.84, 2.75)
SW1/IS2 in the 4th year of life exclusively†
1.55 (1.24, 1.93)
1.17 (0.48, 2.85)
Longstanding illness
1.52 (1.24, 1.87)
1.43 (0.71, 2.86)
Limiting longstanding illness
3.11 (2.23, 4.34)
1.48 (0.12, 18.05)
SW1/IS2at both the child’s 1st & 4th years of life †
1.52 (1.30, 1.76)
1.71 (0.89, 3.27)
1.20 (1.04, 1.39)
1.32 (0.78, 2, 23)
1.69 (1.26, 2.25)
8.01 (2.83, 22.66)
1-SW: Social Welfare; 2-IS: Income support; † Reference category = Not in receipt of SW1/IS2 at both the child’s 1st & 4th years of life ; Models are adjusted for maternal smoking, child’s gender, age, birth order & birth weight, household size & mother’s education

31. Odds ratios for growth delay at 4 years ½, QLSCD, Z. Ehounoux. L
Odds ratios for growth delay at 4 years ½, QLSCD, Z. Ehounoux. L. Séguin. M.V. Zunzunegui. L. Gauvin. B. Nikiéma (JECH, 2009)
Unadjusted OR
(95% CI)
Adjusted OR†
Score of lack of money for basic needs >=3
No lack of money 1
At 2.5 years old only
1.6 ( )
1.5 ( )
At 4 years old only
0.7 ( )
0.7 ( )
Both at 2.5 and 4 years old
2.9 (1.3 – 6.2)
3.4 (1.5 – 7.7)
† Adjusted for the child age, gender, birth rank, presence of intra-uterine growth retardation, duration of breastfeeding, maternal height and education.

32. Obesity at 4 years ½ in relation with duration of poverty and maternal BMI*, J. Rivest. L. Séguin. L. Gauvin. B. Nikiéma
Maternal BMI
Adjusted for child’s characteristics (sex, birth weight), mother’s characteristics (age, education, body mass index, presence of a partner, smoking during pregnancy), and child’s life habits (TV, computer, fruit consumption)

33. Dynamics of Poverty: multilevel analysis
Concurrent Poverty : poverty measured synchronously with the assessment of the health outcome
Lag of Poverty : poverty status recorded at the previous measurement occasion
Cumulative Poverty : total number of measurement occasions during which a child was deemed to be living in conditions of poverty

34. Analytic Strategies: Effects of Concurrent Poverty and Lagged Poverty
Multilevel Models for Count Data (Poisson regression)
Growth Curve Analysis
2 Hierarchical Levels
Level 1=measurement occasion ;
Level 2=children
Laplace Approximation (Laplace)

35. Concurrent effects of Poverty at 41 months
# Asthma Attacks 1
# Acute Infections 2
Event Rate Ratio
(95% CI)
Change due to concurrent poverty 
Sufficient income
1.00
Insufficient income
1.11
( )
1.04
( )
1-Adjusted for child’s sex and birth rank, type of family, mother’s age and education
2- Adjusted for child’s sex, use of daycare center, mother’s education and immigration status

36. Lagged Effects of Poverty at 41 months
# Asthma Attacks 1
# Acute Infections 2
Event Rate Ratio
(95% CI)
Change due to poverty at the previous measurement occasion
Sufficient income
1.00
Insufficient income
1.28
( )
1.10
( )
1-Adjusted for child’s sex and birth rank, type of family, mother’s age and education;
2 -Adjusted for child’s sex, use of daycare center, mother’s education and immigration status

37. Analytic Strategies for Effects of Cumulative Poverty
Multilevel Multivariate Response Analysis
Level 1: Health outcome at each measurement occasion
Level 2: Children
Separate fixed effects at each occasion
Accounting for within-occasion variance and between-occasion covariance

38. Cumulative Effects of Poverty
17 months
29 months
41 months
Event Rate Ratio
# of Asthma Attacks 1
No period with insufficient income
1.00
1 period of poverty
1.71
2.14*
1.38
2 periods of poverty
1.77*
2.28*
1.34
3 periods of poverty
2.32*
2.66*
4 periods of poverty
2.90*
# of acute infections2
1.18
1.14
1.05
1.09
1.12
1.07
1.16
1.13
1-Adjusted for child’s sex and birth rank, type of family, mother’s age and education; 2 -Adjusted for child’s sex, use of daycare center, mother’s education and immigration status; * p < .05

39. Conclusions from multilevel analysis: Timing & duration of poverty matter for child health
Exposure to poverty may result in health problems at a later time
Poverty recorded at the previous measurement occasion is associated with current health outcomes
Accumulation of poverty insults may result in greater risk of health problems among young children
Association between greater number of periods spent living in poverty & greater number of asthma attacks

40. Objectives of the study on asthma attacks between 5 & 7 years old
The objectives of this study are to examine:
if the presence of asthma attack is related to the timing and duration of poverty among 5 to 7 years old children from the QLSCD.
the role of exposure to cumulative adversities before 4 years old in the occurrence of asthma attack among these 5 to 7 years old children.

41. Measure of asthma attacks
Mothers reported if their child experienced an asthma attack during the previous 12 months.

42. Index of psychosocial adversity
Index of psychosocial adversity <4 years old:
Single parent family, dysfunctional family, maternal depression, low social support, neighborhood perceived as unsafe by the mother.

43. Chronic Poverty before 4 Years Old and Exposure to Adversity. QLSCD
Adversities
Never
poor
n=1263
Chronic
poverty
n=264
Single parent family
4.9%
36.6%
Dysfunctional family (highest quartile)
21.0%
37.9%
Maternal depression
19.7%
46.4%
Neighborhood perceived unsafe by mother
8.3%
24.6%

44. Psychosocial adversity before 4-Years old as a function of poverty status at 6-7- yrs old. QLSCD
Exposure to poverty
Never poor
Chronic poverty
Scores of psychosocial adversities < 4-yrs old N %
590
55.5 38
15.0 1
311
29.2 72
28.3 2
116
10.9 73
28.7
3-5 47
4.4 71
28.0

45. Frequency of asthma attack according to some characteristics of the child. QLSCD%
(N)
P-value
Total sample
7.7
(124)
Timing of poverty
0.001
No episode of poverty
6.5
(69)
Poor < 4 yrs old only
5.8
(13)
Poor at 5-7 yrs old only
14.3
(10)
Chronic poverty
12.6
(32)
Asthma in mother or father
< 0.001 No
6.3
(82)
Yes
13.4
(29)
Psychosocial adversity index
0.407
Score 0
7.1
(51)
Score 1
6.9
(33)
Score 2
9.0
(23)
Score 3-5
10.3
(17)

46. Multivariate analysis
Logistic regressions
Examining potential interactions between poverty and psychosocial adversity regarding asthma attacks among children.

47. Multivariate model: The multivariate model is adjusted for:
exposure to smoke from tobacco at home
living in presence of a pet at 5-months old
duration of breastfeeding
the mother’s educational level
No interactions were demonstrated.

48. Probability of an asthma attack between 5 and 7 yrs old
Probability of an asthma attack between 5 and 7 yrs old. QLSCD Odds ratios (OR) and 95 % confidence interval (CI) OR
95% CI
Duration of poverty
No episode of poverty (ref)
1.0
Transitory poverty
(<4yrs old only or at 5-7 yrs old only)
1.2
( )
Chronic poverty
2.0
( )
Psychosocial adversity (ref=0)
Score 1
0.9
( )
Score 2
1.1
( )
Score 3-5
( )
Preterm birth (ref = no)
Yes
2.3
( )
Asthma in mother or father (ref=no)
2.2
( )

49. Timing of poverty
When we examined separately the exposure to transitory poverty before 4 years old (early poverty) there was no significant relationship with the frequency of asthma attacks.
In that analysis we observed a higher probability of an asthma attack among those who were poor chronically compared to those who were never poor.

50. Early psychosocial adversities and asthma attacks at 5 to 7 years old
While the gradient of the cumulative psychosocial index before 4 years is in the expected direction, it is not associated with the occurrence of an asthma attack between 5 and 7 years old when family poverty is accounted for.
The link between poverty and child asthma attack is present whatever the level of education of the mother.

51. Limitations of the QLSCD
Relatively small number of participants.
Lack of information on:
severity of health problems
exposure to other risk factors
management and treatment of asthma.

52. Strengths of the QLSCD A longitudinal prospective design
Large participation rates
Data collected annually at home
trained interviewers
validated scales.

53. What have we learned from the QLSCD? (1)
A large number of Quebec children are growing up in poverty conditions;
Poor children are exposed to multiple adversities;
Links between poverty and children’s health are complex:
Exposure to poverty must last a certain time before affecting a child’s health;
The relationship can vary with different health outcomes and at different ages;
There might be interactions with parents’ characteristics or other variables.

54. What have we learned from the QLSCD? (2)
An insufficient family income during childhood has an impact on the health of children separately from the mother’s level of education;
Chronic stress associated with poverty and its exposure to adversities might be one explicative element, an hypothesis that we are examining in our 10 years old data involving biomarkers.

55. Future research Other studies are necessary to clarify
The mediating or modifying roles of exposure to diverse psychosocial risk factors regarding the likelihood of health problems among poor children;
At what age early poverty might demonstrate its impact on one’s health.

56. Acknowledgments
These studies were funded by the Canadian Institutes of Health Research Grant #200309MOP and Grant #200609MOP
The Institut de la Statistique du Québec, Direction Santé Québec was responsible for the data collection and validation of the data base.
The GRIS receives infrastructure funding from the Fonds de la recherche en santé du Québec (FRSQ)
This presentation was prepared with the help of Béatrice Nikiéma and Lise Gauvin