Socioeconomic position and trajectories of growth and adiposity across childhood
description
Transcript of Socioeconomic position and trajectories of growth and adiposity across childhood
Socioeconomic position and trajectories of growth and adiposity across childhood
Laura Howe, Social Medicine, University of Bristol
Inequalities in growth and adiposity•Socioeconomic disadvantage is associated
with:1.Shorter stature2.Greater adiposity
•Little is known about when the socioeconomic differentials appear
Objectives• Model trajectories of growth across
childhood:1. Height2. Adiposity
• Explore how these growth curves differ by socioeconomic position (SEP)
Research questions
•Do the overall patterns of growth and adiposity change differ by SEP?
•What is the magnitude of socioeconomic differentials at different ages?
•Are there gender differences in the patterns of socioeconomic differentials?
Methods
Height and weight data in ALSPAC1. Birth weights/lengths
(obstetric records & ALSPAC staff visiting hospitals)
2. Routine child health records(health visitors, up to 4 measures per child)
3. Research clinics (CiF and Focus)
4. Questionnaires (mother-reports, up to 4 per questionnaire)
Data – birth to ten yearsHeight Weight
Boys N= 7194Median = 5IQR = 2-8
N= 7248Median = 5IQR = 3-8
Girls N= 6733Median = 5IQR = 2-8
N= 6781Median = 5IQR = 3-8
Adiposity measures
•Ponderal index (kg/m3) for 0-2 years
•BMI (kg/m2) for 2-10 years
Analysis 11. Fractional polynomials to estimate
overall shape
2. Identification of rough spline points
3. Optimisation of spline points
Analysis 2
•Random effects multi-level models in MLwiN
•Individual-level residuals provide an individual’s deviation from the average(intercept and slope for each period)
•Interactions with SEP
Results
•Overall shapes of curves did not differ by SEP
•Spline points were therefore estimated for all SEP groups combined
4060
8010
012
014
0he
ight
(cm
)
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102108114120Age (months)
HeightSpline points
Boys: 3, 10, 29 months
Girls: 2, 11, 32 months
Boys’ mean heights by maternal education
Age (months)Less than O-Level O-Level A-Level
Degree or above
12 76.18 76.41 76.43 76.48
60 108.76 109.36 109.40 109.76
120 140.56 141.40 141.36 141.97
By 10 years: 1.4cm difference between highest and lowest groups
Girls’ mean heights by maternal education
Age (months) Less than O-Level O-Level A-Level Degree or above
12 75.24 75.45 75.31 75.49
60 107.88 108.47 108.50 109.10
120 139.68 140.18 140.69 141.40
By 10 years: 1.7cm difference between highest and lowest groups
Ponderal IndexSpline points
Boys: 2 months
Girls: 1, 4 months18
2022
2426
Pon
dera
l Ind
ex (k
g/m
3)
0 3 6 9 12 15 18 21 24Age (months)
Boys’ ponderal index by maternal education
Age (months) Less than O-Level O-Level A-Level Degree or above
6 25.33 25.49 25.48 25.36
12 23.17 23.29 23.27 23.18
18 21.01 21.10 21.06 21.00
24 18.85 18.91 18.85 18.82
Age (months) Less than O-Level O-Level A-Level Degree or above
6 25.68 25.74 25.73 25.48
12 23.34 23.35 23.42 23.17
18 21.00 20.95 21.12 20.86
24 18.66 18.56 18.82 18.55
Girls’ ponderal index by maternal education
BMISpline points
Boys: 56, 67, 73, 79,
105 months
Girls: 60, 65, 75, 81,
103 months
1616
.517
17.5
BM
I (kg
/m2)
24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120Age (months)
Conclusions: Height•Socioeconomic differentials in height are
largely established by birth length and growth between 1 and 3 years
•Socioeconomic differentials in height are greater for girls than boys
•By 6 years-old there is a clear height gradient across all four categories of maternal education for girls. Intermediate education groups remain similar for boys
Implications: Height•Pre-natal and early life factors are the
most important determinant of socioeconomic differentials in height
Conclusions: Ponderal Index
•There is no clear socioeconomic gradient in ponderal index in the first 2 years of life
Conclusions: BMI•From 4 years onwards, boys whose mothers
are educated to degree-level have lower BMI•There is no BMI gradient across other
categories of maternal education
•From 4 years onwards, girls whose mothers are educated to degree-level have lower BMI
•Inequalities are wider in girls, and there is a clearer gradient across all categories of maternal education
Implications: Adiposity•Socioeconomic inequalities in adiposity
are established early in childhood•Interventions could be aimed at pre-
school and early-school children
Remaining questions
•WHY are inequalities wider in girls?
•Cohort effects?
Next steps•Variables for ALSPAC archive will be
available for all to use
•Associations of growth with other childhood outcomes/exposures
•Modelling growth later into childhood to include puberty
Acknowledgements
•Kate Tilling, Debbie Lawlor, Bruna Galobardes, Paul Clarke, Fiona Steele