Child Growth, Puberty, Adolescent Pregnancy, and Adult Anthropometric Outcomes Open Access

Lundeen, Elizabeth Ann (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/3b591862c?locale=en
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Abstract

Low- and middle-income countries (LMICs) undergoing the nutrition transition face the dual burden of both stunting and rising obesity prevalence among children. Programs aimed at improving nutrition in the first 1,000 days and beyond seek to improve children's linear growth, along with the associated cognitive, schooling, and adult income benefits. The challenge is to promote nutrition that improves linear growth, while not increasing obesity among children in LMICs. Longitudinal data with numerous anthropometric measurements from birth to young adulthood are needed to better understand child growth in LMICs. We used data from nine cohorts in LMICs to explore child growth patterns, including stunting and recovery from stunting, incidence of obesity, pubertal development, and associations with adult anthropometric outcomes. We found there is substantial growth recovery among children who are stunted post-infancy. We contributed to the debate on evaluating the existence of catch-up growth in a population by showing that from age 2y to adulthood, mean height-for-age z scores increased, despite increasing absolute height deficits from the reference population. We found that in South Africa, overweight and obesity were not widely prevalent among boys; however, among girls, the combined prevalence increased throughout childhood, and by late adolescence had reached levels seen in higher income countries. Interventions to prevent overweight and obesity among girls should target the early childhood and peri-pubertal years. We found that among males and females, there was a strong positive association between both height and body mass index (BMI) in early childhood and the tempo of pubertal development. Among females, greater childhood height and BMI were also associated with earlier pubertal development. We concluded that the previously observed relationship between pubertal timing and adult risk of obesity is largely explained by the association of childhood BMI with both puberty and adult BMI. The prevention of childhood obesity is critical, due to its association with both adult obesity and early puberty. Carefully designed interventions are needed to improve linear growth among children in LMICs, while not increasing obesity. Improving child growth could impact pubertal development, and interventions are needed to mitigate the social and psychological consequences of early puberty.

Table of Contents

Chapter 1: Introduction. 1

Specific Aim One. 2

Specific Aim Two. 3

Specific Aim Three. 3

Specific Aim Four. 4

Chapter 2: Background. 5

The Nutrition Transition. 5

The First 1,000 Days Agenda. 6

Global Changes in Pubertal Development. 7

Understanding Child Growth and Development in LMICS. 10

Contribution of This Dissertation. 11

Chapters 1 and 2 References. 14

Chapter 3: Growth faltering and recovery in children ages 1 to 8y in four low- and middle-income countries: Young Lives. 17

Abstract. 18

Introduction. 20

Methods. 21

Young Lives Study. 21

Data Cleaning and Analysis. 22

Characterizing Growth.. 23

Results. 24

Discussion. 26

Chapter 3 References. 35

Chapter 4: Height-for-age z scores increase despite increasing height deficits among children in five developing countries. 37

Abstract. 39

Introduction. 41

Methods. 42

Statistical Methods. 43

Results. 44

Discussion. 45

Chapter 4 References. 53

Chapter 5: Adolescent pregnancy and attained height among Black South African girls: matched-pair prospective study. 55

Abstract. 56

Introduction. 58

Methods. 59

Statistical Methods. 61

Results. 62

Discussion. 63

Conclusion. 67

Chapter 5 References. 72

Chapter 6: Sex differences in obesity incidence: 20-year prospective cohort in South Africa. 74

Abstract. 76

Introduction. 78

Methods. 79

Results. 81

Discussion. 83

Conclusion. 86

Chapter 6 References. 94

Chapter 7: Early Life Determinants of Pubertal Development in South African Adolescents. 96

Abstract. 97

Introduction. 99

Methods. 101

Data Management. 102

Results. 106

Discussion. 109

Conclusion. 114

Chapter 7 References. 133

Chapter 8: Association of Pubertal Timing and Trajectory with Adult Height and Body Mass Index in South African Adolescents. 136

Abstract. 137

Introduction. 140

Methods. 142

Data Management. 143

Results. 147

Discussion. 150

Conclusion. 156

Chapter 8 References. 167

Chapter 9: Summary, Conclusions, and Implications. 170

Discussion of the Key Findings for Each Specific Aim. 172

Specific Aim One. 172

Specific Aim Two. 175

Specific Aim Three. 176

Specific Aim Four. 181

Strengths.184

Limitations. 185

Conclusions. 186

Chapter 9 References. 188

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