Longitudinal Trajectories of Gestational Thyroid Function: A New Approach to Better Understand Changes in Thyroid Function
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Context
Most studies of thyroid function changes during pregnancy use a cross-sectional design comparing means between groups rather than similarities within groups.
Objective
Latent class growth analysis (LCGA) is a novel approach to investigate longitudinal changes that provide dynamic understanding of the relationship between thyroid status and advancing pregnancy.
Design
Prospective observational study with repeated assessments.
Setting
General community.
Patients
Eleven hundred healthy women were included at 12 weeks’ gestation.
Main Outcome Measures
The existence of both free T4 (fT4) and TSH trajectories throughout pregnancy determined by LCGA.
Results
LCGA revealed three trajectory classes. Class 1 (n = 1019; 92.4%), a low increasing TSH reference group, had a gradual increase in TSH throughout gestation (from 1.1 to 1.3 IU/L). Class 2 (n = 30; 2.8%), a high increasing TSH group, displayed the largest increase in TSH (from 1.9 to 3.3 IU/L). Class 3 (n = 51; 4.6%), a decreasing TSH group, had the largest fall in TSH (from 3.2 to 2.4 IU/L). Subclinical hypothyroidism at 12 weeks occurred in up to 60% of class 3 women and was accompanied by elevated thyroid peroxidase antibodies (TPO-Ab) titers (50%) and a parental history of thyroid dysfunction (23%). In class 2, 70% of women were nulliparous compared with 46% in class 1 and 49% in class 3.
Conclusions
LCGA revealed distinct trajectories of longitudinal changes in fT4 and TSH levels during pregnancy in 7.4% of women. These trajectories were correlated with parity and TPO-Ab status and followed patterns that might reflect differences in pregnancy-specific immune tolerance between nulliparous and multiparous women.
Most studies of thyroid function changes during pregnancy use a cross-sectional design comparing means between groups rather than similarities within groups.
Objective
Latent class growth analysis (LCGA) is a novel approach to investigate longitudinal changes that provide dynamic understanding of the relationship between thyroid status and advancing pregnancy.
Design
Prospective observational study with repeated assessments.
Setting
General community.
Patients
Eleven hundred healthy women were included at 12 weeks’ gestation.
Main Outcome Measures
The existence of both free T4 (fT4) and TSH trajectories throughout pregnancy determined by LCGA.
Results
LCGA revealed three trajectory classes. Class 1 (n = 1019; 92.4%), a low increasing TSH reference group, had a gradual increase in TSH throughout gestation (from 1.1 to 1.3 IU/L). Class 2 (n = 30; 2.8%), a high increasing TSH group, displayed the largest increase in TSH (from 1.9 to 3.3 IU/L). Class 3 (n = 51; 4.6%), a decreasing TSH group, had the largest fall in TSH (from 3.2 to 2.4 IU/L). Subclinical hypothyroidism at 12 weeks occurred in up to 60% of class 3 women and was accompanied by elevated thyroid peroxidase antibodies (TPO-Ab) titers (50%) and a parental history of thyroid dysfunction (23%). In class 2, 70% of women were nulliparous compared with 46% in class 1 and 49% in class 3.
Conclusions
LCGA revealed distinct trajectories of longitudinal changes in fT4 and TSH levels during pregnancy in 7.4% of women. These trajectories were correlated with parity and TPO-Ab status and followed patterns that might reflect differences in pregnancy-specific immune tolerance between nulliparous and multiparous women.
Date Issued
2018-05-28
Date Acceptance
2018-05-15
Citation
The Journal of Clinical Endocrinology & Metabolism, 2018, 103 (8), pp.2889-2900
ISSN
0021-972X
Publisher
Oxford University Press
Start Page
2889
End Page
2900
Journal / Book Title
The Journal of Clinical Endocrinology & Metabolism
Volume
103
Issue
8
Copyright Statement
© 2018 Endocrine Society. This is a pre-copy-editing, author-produced version of an article accepted for publication in Journal of Clinical Endocrinology and Metabolism following peer review. The definitive publisher-authenticated version: Victor Pop, Maarten Broeren, Hennie Wijnen, Joyce Endendijk, Anneloes van Baar, Wilmar Wiersinga, Graham R Williams; Longitudinal Trajectories of Gestational Thyroid Function: A New Approach to Better Understand Changes in Thyroid Function, The Journal of Clinical Endocrinology & Metabolism, Volume 103, Issue 8, 1 August 2018, Pages 2889–2900, is available online at: https://dx.doi.org/10.1210/jc.2017-02556
Subjects
1103 Clinical Sciences
1114 Paediatrics And Reproductive Medicine
Endocrinology & Metabolism
Publication Status
Published
Date Publish Online
2018-05-28