Variables Contributing to Thyroid (Dys)Function in Pregnant Women: More than Thyroid Antibodies?

Veltri, Flora; Poppe, Kris

doi:10.1159/000488279

Cited by 18 publications

(19 citation statements)

References 75 publications

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“…Exploring a wide range of potential explanatory factors for the observed ethnic differences was beyond the scope of this study. However, other than genetic determinant factors and the amount and different type of human chorionic gonadotropin between groups [ 17 , 23 ], the differences could partly be related to insulin resistance, as seen in South Asians [ 24 ], and nutritional factors such as iron deficiency [ 25 ]. Nevertheless, additional adjustments for ferritin (indicator of iron deficiency) or the homeostasis model assessment of insulin resistance had minimal impact on the ethnic differences in TSH (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Thyroid Function During Pregnancy in A Multiethnic Population in Norway

Sletner

Jenum

Qvigstad

et al. 2021

Journal of the Endocrine Society

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Context Ethnic differences in thyroid function during pregnancy have been reported. However, it is unclear if this is equally valid across ethnic groups within multiethnic populations. Objective We aimed to assess ethnic differences in thyrotropin (TSH) and free thyroxine (FT4), and the prevalence of thyroid dysfunction and thyroid autoimmunity during pregnancy. Methods In a population-based cohort of 785 pregnant women in Oslo, Norway, TSH, FT4, and thyroid peroxidase antibodies (TPO Abs) were measured twice: at gestational week (GW) 15 and 28, and urine iodine concentration at GW 15. Associations were assessed using multivariate linear regression. Results We found ethnic differences in TSH levels at both time points, but not for fT4. South Asians had 0.42 mU/L (95% CI, 0.20-0.64) higher TSH than Europeans in GW 15. This difference persisted after adjusting for covariates (including TPO Ab positivity and iodine status), and increased further as pregnancy progressed. In contrast, East Asians had the lowest TSH. No new cases of overt hypothyroidism were detected in early pregnancy, but subclinical hypothyroidism was found in 6.6% among all, highest in South Asians (14.2%). Hyperthyroidism early in pregnancy was observed in 3.7% (almost all subclinical), highest in East Asians (11.9%). The prevalence of TPO Ab positivity was 4%, highest in South Asians (8%). Conclusion In a multiethnic population of presumably healthy women, we found ethnic variations in TSH but not FT4 levels throughout pregnancy. South Asians had higher TSH and more subclinical hypothyroidism, not explained by their higher prevalence of TPO Ab positivity. Larger studies are needed to define ethnic- and trimester-specific reference ranges in pregnancy.

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Section: Discussionmentioning

confidence: 99%

Thyroid Function During Pregnancy in A Multiethnic Population in Norway

Sletner

Jenum

Qvigstad

et al. 2021

Journal of the Endocrine Society

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“…Another aspect relates to the clinical implications of an association between thyroid disease and body weight. For the management of thyroid disease in pregnancy, it remains uncertain whether the diagnostic procedure would benefit from the use of reference ranges for thyroid function tests that are stratified by categories of maternal BMI 12,29 . Moreover, measurement of TSH should be considered in clinical practice when maternal BMI is above 40 kg/m 2 (morbid obesity) 2 .…”

Section: Discussionmentioning

confidence: 99%

Maternal thyroid disease and adiposity in mother and child

Andersen

Liew

et al. 2020

Clinical Endocrinology

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Objective Thyroid hormones are crucial developmental factors, and thyroid disease in pregnant women is a concern. Overweight and obesity are also important health concerns, and we hypothesized that in utero exposure to maternal thyroid disease could programme the foetus to development of adiposity. Design Cohort and case‐cohort studies. Participants Pregnant women from the Danish National Birth Cohort and their 7‐year‐old children. Measurements Maternal thyroid disease (hyperthyroidism and hypothyroidism) was assessed from registrations of diagnoses and treatment (n = 71 706) or from the measurement of thyroid‐stimulating hormone (TSH) in a stored blood sample from the early pregnancy (n = 7624). Maternal prepregnancy body mass index (BMI) and child BMI at 7 years of age were used to define overweight and obesity, and associations were evaluated using regression models adjusting for potential confounders. Results No association was found between maternal thyroid disease in pregnancy and child overweight (hyperthyroidism: adjusted risk ratio (aRR): 1.02 (95% confidence interval (CI): 0.58‐1.82); hypothyroidism: 1.31 (0.86‐1.97)) or obesity (hyperthyroidism: 0.96 (0.53‐1.75); hypothyroidism: 1.25 (0.76‐2.05)). On the other hand, pregnant women with hypothyroidism in early pregnancy had a higher risk of being overweight (aRR: 1.20 (95% CI: 1.03; 1.41)) and obese (1.45 (1.07; 1.96)), whereas women with hyperthyroidism had a lower risk of being overweight (0.79 (0.64; 0.98)). Conclusions Results provide no evidence that maternal thyroid disease in pregnancy programmes adiposity in the child, but corroborate an association between maternal thyroid disease and adiposity in the mother.

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“…Additionally, women with subclinical hypothyroidism show an abnormal response to thyroidal stimulation by β-hCG [14]. It is not well known what the relative importance of maternal personal conditions is such as weight, iodine-enriched multivitamin complexes intake [15,16], smoking habit and lifestyle [17] in thyroid function throughout the pregnancy. The aim of our research is to study the potential contribution of different factors in maternal thyroid function variability in pregnant women without maternal or fetal risk factors, as well as to identify profiles of low availability of maternal thyroxine (T4).…”

Section: Introductionmentioning

confidence: 99%

Thyroid Function Variability in a Cohort of Healthy Pregnant Women: Effect of BMI, Smoking and Iodized Salt Consumption

Velasco¹,

Soldevila

MartínezMondejar

et al. 2020

LOJPCR

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Introduction: It remains unclear to what extent intrinsic maternal characteristics, lifestyle or diet and dietary supplements contribute to explain the variability of maternal thyroid function. The aim of this study was to analyse the effect of age, parity, pregestational body mass index (BMI), beta human chorionic gonadotropin (β-hCG), thyroid autoantibodies, smoking habit and use of vitamins/supplements on maternal thyroid function variability throughout pregnancy. Methods:A prospective, observational study was carried out including 339 healthy pregnant women from their first to their third trimester. Clinical and biological variables were registered at each stage. Univariate correlation and multiple linear regression analysis for thyroid parameters were performed in the three trimesters.Results: Thyrotropin (TSH) in the first trimester (1T) was dependent on free thyroxine (FT4), maternal age, β-hCG and smoking habit. FT4 levels in the 1T were significantly lower in obese women (0.937±0.078ng/dl), compared with overweighed (0.981±0.14ng/dl) and normal weight women (0.989± 0.98ng/dl) (p=0.012). Multiple linear regression showed that FT4 in all trimesters is significantly dependent on pregestational BMI. Additionally, TSH and FT4 in the 1T were significantly related to TSH and FT4 levels in second and third trimesters, respectively. All studied factors influenced TSH with different degree all-over the pregnancy. Dietary supplements did not modify maternal thyroid function. Conclusion:FT4 availability during the first half of the gestation can be hindered by maternal overweight/obesity. Beside age, obesity and smoking, TSH and FT4 in the 1T are very important regarding thyroid function variability in further stages of the pregnancy.

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Variables Contributing to Thyroid (Dys)Function in Pregnant Women: More than Thyroid Antibodies?

Cited by 18 publications

References 75 publications

Thyroid Function During Pregnancy in A Multiethnic Population in Norway

Thyroid Function During Pregnancy in A Multiethnic Population in Norway

Maternal thyroid disease and adiposity in mother and child

Thyroid Function Variability in a Cohort of Healthy Pregnant Women: Effect of BMI, Smoking and Iodized Salt Consumption

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