Maternal hypothyroxinaemia in pregnancy is associated with obesity and adverse maternal metabolic parameters.
Hattersley, Andrew T.
European Journal of Endocrinology
BioScientifica & European Society of Endocrinology
OBJECTIVE: Subclinical hypothyroidism and isolated hypothyroxinaemia in pregnancy have been associated with an increased risk of gestational diabetes. We aimed to ascertain if these women have a worse metabolic phenotype than euthyroid pregnant women. DESIGN, SUBJECTS AND METHODS: We recruited 956 healthy Caucasian women with singleton, non-diabetic pregnancies from routine antenatal clinics. Detailed anthropometric measurements (including BMI and skinfold thickness) and fasting blood samples (for TSH, free thyroxine (FT4), free triiodothyronine (FT3), HbA1c, lipid profile, plasma glucose and insulin resistance (HOMA-IR) analysis) were obtained at 28 weeks gestation. RESULTS: In comparison to euthyroid women (n=741), women with isolated hypothyroxinaemia (n=82) had significantly increased BMI (29.5 vs 27.5 kg/m(2), P<0.001), sum of skinfolds (57.5 vs 51.3 mm, P=0.002), fasting plasma glucose (4.5 vs 4.3 mmol/l, P=0.01), triglycerides (2.3 vs 2.0 mmol/l, P<0.001) and HOMA-IR (2.0 vs 1.3, P=0.001). Metabolic parameters in women with subclinical hypothyroidism (n=133) were similar to those in euthyroid women. Maternal FT4 was negatively associated with BMI (r=-0.22), HbA1c (r=-0.14), triglycerides (r=-0.17), HOMA-IR (r=-0.15) but not total/HDL cholesterol ratio (r=-0.03). Maternal FT3:FT4 ratio was positively associated with BMI (r=0.4), HbA1c (r=0.21), triglycerides (r=0.2), HOMA-IR (r=0.33) and total/HDL cholesterol ratio (r=0.07). TSH was not associated with the metabolic parameters assessed. CONCLUSIONS: Isolated hypothyroxinaemia, but not subclinical hypothyroidism, is associated with adverse metabolic phenotype in pregnancy, as is decreasing maternal FT4 and increasing FT3:FT4 ratio. These associations may be a reflection of changes in the thyroid hormone levels secondary to increase in BMI rather than changes in thyroid hormone levels affecting body weight and related metabolic parameters.
National Institute for Health Research (NIHR)
Disclaimer: this is not the definitive version of record of this article.This manuscript has been accepted for publication in European Journal of Endocrinology, but the version presented here has not yet been copy-edited, formatted or proofed. Consequently, Bioscientifica accepts no responsibility for any errors or omissions it may contain. The definitive version is available at doi: 10.1530/EJE-15-0866.
© 2016 The authors Published by Bioscientifica Ltd. This work is licensed under a Creative Commons Attribution 3.0 Unported License.
Vol. 174, pp. 51 - 57
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