Initiation and progression of puberty in girls, and environmental exposures in a contemporary longitudinal cohort Open Access

Christensen, Krista Liv Yorita (2009)

Permanent URL: https://etd.library.emory.edu/concern/etds/3x816m70c?locale=en
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Abstract


Abstract

Initiation and progression of puberty in girls, and environmental exposures in a
contemporary longitudinal cohort
By Krista Yorita Christensen
Puberty is occurring earlier than in the past, a secular trend which may be due in part to
exposure to endocrine disrupting chemicals such as persistent organic pollutants. In this
dissertation, the initiation and progression of pubertal development were described for
female offspring participating in the Avon Longitudinal Study of Parents and Children
(ALSPAC). Self-reported breast and pubic hair and age at menarche were collected via
mailed questionnaire from 8-14 years. Ages at entry into each stage of breast and pubic
hair development, age at menarche, and duration of puberty were estimated using
survival analysis. The correlation between age at beginning breast and pubic hair
development was estimated using a maximum likelihood approach. Factors associated
with initiation pathway, and with breast and pubic hair stage were assessed using
polytomous logistic regression, and ordinal probit analyses, respectively. The association
between age at menarche and exposure to persistent organic pollutants was assessed in
two ways. First, a nested case-control study was conducted among ALSPAC participants
to determine association between earlier (<11.5 years) or later age at menarche, and
maternal serum concentration of polyfluoroalkyl compounds (PFCs). Second, data from
the 2003-2004 National Health and Nutrition Examination Survey (NHANES) were used
to construct survival analysis models for the association between age at menarche, and
serum concentrations of polybrominated diphenyl ethers (PBDEs), polybrominated
biphenyl (PBB) 153, polychlorinated biphenyls (PCBs), and PFCs.
On average, girls in the ALSPAC began breast and pubic hair development at the ages of
10.2 and 10.95 years. The correlation between these ages was estimated to be 0.5. Most
girls had synchronous initiation of breast and pubic hair development (46.3%), or started
breast development first (42.1%). Age at menarche (mean=12.87 years) and duration of
puberty (mean=2.7 years) both varied by initiation pathway. Both maternal and child
characteristics were associated with initiation pathway, and with breast and pubic hair
stage. PCBs and PBDEs were associated with altered age at menarche, but no
relationship was seen for PBB 153 or PFCs. Further research is needed to determine the
impact of these and other pollutants on other growth parameters, and periods of
vulnerability for exposure.

Links to final published versions of articles resulting from this dissertation:

http://dx.doi.org/10.1016/j.envint.2010.08.007

http://dx.doi.org/10.1016/j.jadohealth.2010.02.005

http://dx.doi.org/10.1016/j.annepidem.2010.02.005

Table of Contents

Table of Contents Chapter 1: Study Motivation I. Study Motivation II. Study Aims III. Study Contributions Chapter 2: Literature review I. Pubertal development of girls (1) Events and processes (a) Events and processes in utero (b) Events and processes in childhood (2) Timing (3) Precocious puberty (a) Definition of precocious puberty (b) Causes of precocious puberty (i) Causes of central precocious puberty (ii) Causes of peripheral precocious puberty (c) Treatment of precocious puberty (4) Delayed puberty (a) Definition of delayed puberty (b) Causes of delayed puberty (i) Constitutional delay of puberty (ii) Hypogonadotrophic hypogonadism (iii) Hypergonadotrophic hypogonadism (c) Treatment of delayed puberty (4) Secular trends in pubertal timing (5) Consequences of disrupted puberty (6) Longitudinal studies of pubertal development (a) Longitudinal studies in the United States (i) Bogalusa study (ii) Fels Longitudinal study (iii) Lee study (iv) NHLBI Growth and Health study (b) Longitudinal studies in Europe (i) First Zurich longitudinal study (ii) Young-HUNT study (iii) Swedish Longitudinal Growth Study (iv) Harpenden Growth Study (v) National Child Development Study (vi) Buckler Study (7) Cross-sectional studies of pubertal development: United Kingdom (8) Methodological approaches for studies of pubertal development II. Environmental exposures (1) Overview (2) Brominated flame retardants (a) Evidence from animal studies (b) Evidence from human studies (3) Pesticides, fungicides and dioxins (a) Evidence from animal studies (b) Evidence from human studies (4) Polychlorinated biphenyls (a) Evidence from animal studies (b) Evidence from human studies (5) Polyfluoroalkyl chemicals (a) Evidence from animal studies (b) Evidence from human studies (6) Exposure to persistent organic pollutants in the United States (7) Exposure to persistent organic pollutants in the United Kingdom Chapter 3: Study Design I. Study Design (1) ALSPAC study population (2) ALSPAC data collection (a) Pubertal development ascertainment (b) Environmental exposure ascertainment (c) Additional variables of interest (3) NHANES study population (4) NHANES data collection (a) Pubertal development ascertainment (b) Environmental exposure ascertainment (c) Other variables of interest Chapter 4: Research Objectives and Methods I. Objective 1 (1) Initiation of pubertal development (a) Initiation pathways (b) Distribution of Tanner stages and age at menarche (c) Characterization of the correlation between age at entry into breast and pubic hair development (2) Progression of pubertal development (a) Concordance of stages (b) Progression through stages of development II. Objective 2 (1) Nested case control study of in utero exposure to PFCs and age at menarche (a) Study objective (b) Study design (c) Analysis (2) Effect of POP exposure on age at menarche (a) Study objective (b) Study design (c) Analysis Chapter 5: Initiation of puberty in girls enrolled in a contemporary British cohort I. Introduction II. Methods III. Results IV. Discussion Chapter 6: Characterization of the correlation between ages at entry into breast and pubic hair development I. Introduction II. Methods III. Results IV. Discussion Chapter 7: Progression of puberty in girls enrolled in a contemporary British cohort I. Introduction II. Methods (1) Study population (2) Pubertal assessment (3) Determinants of secondary sexual characteristic development (4) Estimation of length of time between pubertal milestones (5) Covariates III. Results (1) Study population (2) Determinants of secondary sexual characteristic development (3) Estimation of length of time between pubertal milestones IV. Discussion Chapter 8: Exposure to polyfluoroalkyl chemicals during pregnancy is not associated with offspring age at menarche in a contemporary British cohort I. Introduction II. Methods III. Results IV. Discussion Chapter 9: Differences in the pacing of pubertal development by race and environmental exposures I. Introduction II. Methods III. Results IV. Discussion Chapter 10: Conclusions References Appendix A: Institutional Review Board withdrawal notice

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