Publication: Overweight increases risk of first trimester hypothyroxinaemia in iodine-deficient pregnant women.
Issued Date
2014
Resource Type
Language
eng
Rights
Mahidol University
Rights Holder(s)
John Wiley & Sons
Bibliographic Citation
Maternal Child Nutrition. Vol. 10, (2014), 61–71
Suggested Citation
Sueppong Gowachirapant, Melse-Boonstra, Alida, Pattanee Winichagoon, Zimmermann, Michael B. Overweight increases risk of first trimester hypothyroxinaemia in iodine-deficient pregnant women.. Maternal Child Nutrition. Vol. 10, (2014), 61–71. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/30092
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Title
Overweight increases risk of first trimester hypothyroxinaemia in iodine-deficient pregnant women.
Other Contributor(s)
Abstract
Hypothyroxinaemia early in pregnancy may impair fetal brain development. Increased body weight has been associated with low thyroxine concentrations in non-pregnant women. In pregnant women, morbid maternal obesity is a risk factor for thyroid dysfunction. But whether lesser degrees of overweight that are much more common could be a risk factor for hypothyroxinaemia in pregnancy is unclear. The objective of this study was to investigate if overweight increases risk for thyroid dysfunction, and specifically hypothyroxinaemia, in iodine-deficient pregnant women. We performed a cross-sectional study at first hospital visit among healthy Thai pregnant women. We measured weight and height, urinary iodine concentration (UIC), serum thyroid hormones and thyroglobulin. Pre-pregnancy weight and relevant dietary factors were determined by questionnaire, and body mass index (BMI) was used to classify weight status. Among 514 women (mean gestational age, 11 weeks) with a median UIC of 111 μg dL(-1) , indicating mild iodine deficiency, 12% had low free thyroxine (fT4) concentrations: 3% had overt hypothyroidism; 7% had subclinical hypothyroidism; and 8% had isolated hypothyroxinaemia. Based on pre-pregnancy BMI, 26% of women were overweight or obese. In a multiple regression model, BMI was a negative predictor of fT4 (β = -0.20, P < 0.001). Compared to normal weight women, the prevalence ratio (95% CI) of a low fT4 in overweight women was 3.64 (2.08-6.37) (P < 0.01). Iodine-deficient pregnant Thai women who are overweight have a 3.6-fold higher risk of hypothyroxinaemia in the first trimester compared to normal weight women. Targeted screening should consider overweight a potential risk factor for thyroid dysfunction in pregnant women in iodine-deficient areas.