Transcript Birth Spacing and Adolescent Cognitive Level
Author Author Date
Introduction
◦ ◦ ◦ ◦ Hypothesis Significance Definitions Pathway Methods Results Conclusion Q&A
Among the population of adolescents in the study, younger siblings of dyad pairs born further apart from their older siblings will have higher cognitive scores than those born closer to their older siblings.
That is, you’ll be smarter if your parents have you and your sibling further in time apart.
How much time should you plan to set aside to have smart kids?
What makes you smarter than your younger sibling?
Birth spacing # months between sibling birth dates ◦ Cognitive Ability Peabody Picture Vocabulary Test
More attention for child Different interaction between siblings More resources for care
Mostly infant and early childhood samples ◦ ◦ Contradicting results Yes, there is an association 1,2,4,5,7,8, 11 No, there is no association 3,5, 6, 9, 10, 11 Weak controls in adolescent studies
Study of adolescents Stronger control for SES, gender, birth order, family size Different cognitive measure
Introduction
Methods
◦ Study design ◦ Exposure & Outcome variables ◦ Covariates ◦ Models & Interaction Results Conclusion Q&A
Child Health and Development Study Prospective, longitudinal Kaiser Foundation Health Plan, Oakland, California Women and their children born 1959 – 1967 Adolescent Study (born between 1960 – 1963)
229 Older siblings 20,754 20,036 19,605 19,571 9,421 1,900 1,768 384 375 364 35 <2 yrs 135 - Children w/severe anomalies - Multiples - Children whose mother had hypothyroidism - Children not born 1960-1963 - Children not followed in Adolescent Study - Children w/stepsiblings - Children w/>1 sibling - Children w/o Peabody score - Children w/older sibling alive at Adol Study* and < 18 yrs older Younger siblings 38 2-3 yrs 25 3.1-4 yrs 37 > 4 yrs *also excludes 9 records with inconsistent family size between PREPROD and ADOL
Birth space interval = birthday of younger sibling – birthday of older sibling ◦ ◦ ◦ 3 versions of exposure: Categorical exposure Continuous exposure Dual exposure (categorical and continuous)
◦ ◦ Version 1: Categorical (5) Second-born ≤2 years 2.1-3 years 3.1-4 years >4 years First-born Version 2: Continuous (months)
Version 3: Dual ◦ Categorical First-born Second-born ◦ Continuous (months)
◦ ◦ ◦ Continuous Peabody score (points) In general: ◦ ◦ SD = 15 Range = 0 to 160 In sample: Range = 71 to 156 Mean = 117.9
SD = 14.3
maternal age race child sex sibling sex alcohol smoking child age preterm social class marital status low birthweight head circumference delivery type
maternal age race child sex sibling sex alcohol smoking child age preterm social class marital status low birthweight head circumference delivery type
maternal age Smoking race child sex sibling sex alcohol social class child age head circumference low birthweight preterm Significance at p < 0.2
maternal age smoking race child sex sibling sex alcohol social class child age head circumference low birthweight preterm Significance at p < 0.2
maternal age smoking race child sex sibling sex alcohol social class child age head circumference low birthweight preterm Significance: >10% change in coefficient of at least 1 exposure category
maternal age race smoking child age child sex social class
Significance at > 10% change in coefficient of at least 2 exposure categories
Full Categorical Birth spacing Continuous birth spacing Dual birth spacing Model 1 Model 2 Model 3 Restricted Model 4 Model 5 Interaction, Restricted Model 7 • • • Model 8 Model 9 Model 10 Model 6 N/A
Continuous birth spacing variable B = 0.001 , p = 0.13
Tiny magnitude Lowess smoother Pretty linear -20 bandwidth = .8
0 20 40 spacemean 60 80
Continuous exposure model Significance set at p < 0.2: 1.
Birth spacing /race 2.
Birth spacing /child sex Revised model 1.
Significance set at p < 0.2: Birth spacing /child sex 2.
3.
Race /child sex Birth spacing / child sex / race
Introduction Methods
Results
◦ ◦ ◦ ◦ Categorical Model Continuous Model Dual Model Interaction Conclusion Q&A
Characteristic Birth spacing Second- born ≤2 yrs Second- born 2.1-3 yrs Second- born 3.1-4 yrs Second- born >4 yrs First-born Maternal characteristics Upper class (v. lower) White (v. other) Age (years) Smoking (yes v. no) Child characteristics Male (v. female) Age B - -3.1
-0.7
*-9.4
-2.7
*6.7
*7.8
*0.4
*-3.9
1.1
*4.3
95% CI - (-8.9, 2.7) (-7.3, 5.8) (-15.3, -3.5) (-7.2, 1.9) (3.9, 9.5) (4.5, 11.2) (0.2, 0.7) (-6.7, -1.2) (-1.5, 3.8) (2.1, 6.5) * p < 0.05
Characteristic Birth spacing (months) Maternal characteristics Upper class (v. lower) White (v. other) Age (years) Smoking (yes v. no) Child characteristics Male (v. female) Age B *-0.1
95% CI (-0.2, -0.02) *2.3
2.9
0.2
2.4
(2.3, 11.4) (-2.2, 9.5) (-0.2, 0.7) (-8.6, 0.7) 2.2
2.2
(-3.7, 5.1) (-1.6, 7.0) * p < 0.05
Characteristic Birth spacing (months) Maternal characteristics Upper class (v. lower) White (v. other) Age (years) Smoking (yes v. no) Child characteristics Male (v. female) Age B *-0.1
*6.5
*8.0
*0.5
*-3.7
1.1
*4.5
95% CI (-0.2, -0.1) (3.7, 9.2) (4.7, 11.4) (0.2, 0.7) (-6.4, -0.9) (-1.5, 3.8) (2.3, 6.7) * p < 0.05
Characteristic Intercept Birth spacing (years) Maternal characteristics Upper class (v. lower) White (v. other) Age (years) Smoking (yes v. no) Child characteristics Male (v. female) Age Interaction Birth spacing / white Birth spacing / male White / male Birth spacing/white/male β 8 β 9 β 10 β 11 β 2 β 3 β 4 β 5 β 0 β 1 B 95% CI *108.3 (100.7, 115.9) -0.6
(-4.3, 2.8) *5.8
*9.9
0.2
*-4.0
(1.3, 10.2) (1.7, 18.1) (-0.2, 0.6) (-8.6, 0.5) β β 6 7 *10.9
3.0
(0.9, 20.9) (-1.2, 7.3) 0.3
*-8.5
*-11.7
*7.1
(-3.5, 4.1) (-16.6, -0.4) (-22.9, -0.48) (-1.2, 15.5) *p < 0.1
Slope (year) 95% CI White boys Other boys White girls Other girls -1.8
-9.2
-0.5
-0.8
(-3.3, -0.3) (-16.5, -1.9) (-1.9, 1.0) (-4.3, 2.8) Regression equation Y = B 0 Y = B 0 Y = B 0 Y = B 0 + (B 1 + (B 1 + (B 1 + B 8 + B 1 * yr + B 9 + B 11 ) yr + B 3 + B 9 ) yr + B 6 + B 8 ) yr + B 3 + B 6 + B 10 ** holding other covariates constant
160 140 120 100 80 60 40 20 0 Other v. White Boys Birth spacing (years) Other Boys White Boys
160 140 120 100 80 60 40 20 0 Other v. White Girls Birth spacing (years) Other Boys White Boys Other Girls White Girls
Introduction Methods Results
Conclusion
◦ ◦ ◦ Summary Limitations & Strengths Future Directions Q&A
Slight inverse relationship between birth spacing and Peabody score Negligible difference in Peabody score Interaction from gender and race
Small sample size Limited information on first-born siblings ◦ No PREPROD record Unable to compare scores within dyad Operationalizing cognitive ability
◦ ◦ ◦ Statistical rigor Limiting confounders Extensive covariates list Interactions
Bigger sample size ◦ ◦ ◦ Designs that can account for what we could not Different family sizes Intra-family differences in Peabody score Missing covariates Exploring variables underlying interactions
Introduction Methods Results Conclusion ◦
Q&A
Thank you!
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