Increased Pregnancy Loss Rate in Thyroid Antibody Negative Women with TSH Levels between 2.5 and 5.0 in the First Trimester of Pregnancy
The definition of what constitutes a normal TSH during pregnancy is in flux. Recent studies suggested that the first trimester upper limit of normal for TSH should be 2.5 mIU/liter.
The objective of the study was to evaluate the pregnancy loss and preterm delivery rate in first-trimester thyroid peroxidase antibody-negative women with TSH values between 2.5 and 5.0 mIU/liter.
The present study is a component of a recently published large-scale prospective trial that evaluated the impact of levothyroxine treatment on maternal and neonatal complications in thyroid peroxidase-positive women with TSH levels above 2.5 mIU/liter. The present study evaluated 4123 thyroid peroxidase antibody-negative women with TSH levels at or below 5.0 mIU/liter. Women were divided into two groups based on their initial TSH: group A, TSH level below 2.5 mIU/liter, excluding hyperthyroid women defined as an undetectable TSH with an elevated free T(4), and group B, TSH level between 2.5 and 5.0 mIU/liter.
The study was conducted at two ambulatory clinics of community hospitals in southern Italy.
A total of 4123 women were evaluated.
There was no intervention.
The incidence of pregnancy loss and preterm delivery in group A as compared with group B was measured.
The rate of pregnancy loss was significantly higher in group B as compared with group A (6.1 vs. 3.6% respectively, P = 0.006). There was no difference in the rate of preterm delivery between the two groups.
The increased incidence of pregnancy loss in pregnant women with TSH levels between 2.5 and 5.0 mIU/liter provides strong physiological evidence to support redefining the TSH upper limit of normal in the first trimester to 2.5 mIU/liter.
Available from: Birgit Jatzko
- "Moreover, the relationship between thyroid dysfunction and negative outcomes for the mother in terms of miscarriage, preterm delivery and preeclampsia as well as for child in terms of decreased intelligence quotient and birth weight is relatively well known
[15,16]. Even subclinical hypothyroidism without thyroid autoantibodies seems to be associated with the above mentioned problems
[16-19]. Treatment of overt hypothyroidism during pregnancy is, therefore, mandatory and consists of levothyroxine therapy adjusted to achieve normal trimester-specific serum levels of thyroid stimulating hormone (TSH). "
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ABSTRACT: Hashimoto's thyroiditis is the most common endocrinopathy in premenopausal women, and is associated with various gynecological problems, including recurrent miscarriage and unexplained infertility. A possible influence of Hashimoto's thyroiditis on the success of intrauterine insemination seems likely, but has not been evaluated as yet. Therefore, the aim of our study was to retrospectively analyze the impact on intrauterine insemination outcome of thyroid function and markers suggestive for Hashimoto's thyroiditis.
Retrospective cohort study in a tertiary care center of 540 women who underwent Intrauterine Insemination. The clinical pregnancy rate was the main outcome parameters. The following possible influencing factors were tested: thyroid-stimulating hormone (TSH); thyroid autoantibodies; age; body mass index; type of sterility (primary/secondary); parity; male factor; presence of PCO syndrome; ovulation induction; ovarian stimulation; and current thyroid medication.
The overall clinical pregnancy rate was 6.9% (37/540). Age, thyroid hormone supplementation for thyroid-stimulating hormone (TSH) levels >2.5 micro-IU/ml, and ovulation induction with HCG were significantly predictive in the multivariate analysis (p < 0.05) as influencing factors for the pregnancy rate after intrauterine insemination.
Women undergoing intrauterine insemination seem to benefit from a strict thyroid hormone supplementation regimen in order to achieve lower TSH levels.
Available from: Mark Kilby
- "Both maternal hypothyroidism and hyperthyroidism have been associated with a range of malplacentation disorders such as miscarriage, stillbirth , prematurity, pre-eclampsia and fetal growth restriction (Krassas et al., 2010), leading to increased perinatal morbidity and mortality. Even minor perturbations in maternal thyroid activity have been linked to miscarriage (Negro et al., 2010), preterm delivery and placental abruption (Casey et al., 2005). Increasing delay in achieving euthyroidism in pregnancies complicated by maternal thyroid dysfunction has been correlated with greater obstetric risks (Abalovich et al., 2002; LaFranchi et al., 2005), suggesting that key thyroid-responsive events during fetoplacental development are gestational age-dependent and may not be corrected at a later stage of pregnancy. "
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ABSTRACT: Does triiodothyronine (T3) regulate the secretion of angiogenic growth factors and cytokines by human decidual cells isolated from early pregnancy?
T3 modulates the secretion of specific angiogenic growth factors and cytokines, with different regulatory patterns observed amongst various isolated subpopulations of human decidual cells and with a distinct change between the first and second trimesters of pregnancy.
Maternal thyroid dysfunction during early pregnancy is associated with complications of malplacentation including miscarriage and pre-eclampsia. T3 regulates the proliferation and apoptosis of fetal-derived trophoblasts, as well as promotes the invasive capability of extravillous trophoblasts (EVT). We hypothesize that T3 may also have a direct impact on human maternal-derived decidual cells, which are known to exert paracrine regulation upon trophoblast behaviour and vascular development at the uteroplacental interface.
This laboratory-based study used human decidua from first (8-11 weeks; n = 18) and second (12-16 weeks; n = 12) trimester surgical terminations of apparently uncomplicated pregnancies.
Primary cultures of total decidual cells, and immunomagnetic bead-isolated populations of stromal-enriched (CD10+) and stromal-depleted (CD10-) cells, uterine natural killer cells (uNK cells; CD56+) and macrophages (CD14+) were assessed for thyroid hormone receptors and transporters by immunocytochemistry. Each cell population was treated with T3 (0, 1, 10, 100 nM) and assessments were made of cell viability (MTT assay) and angiogenic growth factor and cytokine secretion (immunomediated assay). The effect of decidual cell-conditioned media on EVT invasion through Matrigel(®) was evaluated.
Immunocytochemistry showed the expression of thyroid hormone transporters (MCT8, MCT10) and receptors (TRα1, TRβ1) required for thyroid hormone-responsiveness in uNK cells and macrophages from the first trimester. The viability of total decidual cells and the different cell isolates were unaffected by T3 so changes in cell numbers could not account for any observed effects. In the first trimester, T3 decreased VEGF-A secretion by total decidual cells (P < 0.05) and increased angiopoietin-2 secretion by stromal-depleted cells (P < 0.05) but in the second trimester total decidual cells showed only increased angiogenin secretion (P < 0.05). In the first trimester, T3 reduced IL-10 secretion by total decidual cells (P < 0.05), and reduced granulocyte macrophage colony stimulating factor (P < 0.01), IL-8 (P < 0.05), IL-10 (P < 0.01), IL-1β (P < 0.05) and monocyte chemotactic protein -1 (P < 0.001) secretion by macrophages, but increased tumour necrosis factor-α secretion by stromal-depleted cells (P < 0.05) and increased IL-6 by uNK cells (P < 0.05). In contrast, in the second trimester T3 increased IL-10 secretion by total decidual cells (P < 0.01) but did not affect cytokine secretion by uNK cells and macrophages. Conditioned media from first trimester T3-treated total decidual cells and macrophages did not alter EVT invasion compared with untreated controls. Thus, treatment of decidual cells with T3 resulted in changes in both angiogenic growth factor and cytokine secretion in a cell type-specific and gestational age-dependent manner, with first trimester decidual macrophages being the most responsive to T3 treatment, but these changes in decidual cell secretome did not affect EVT invasion in vitro.
Our results are based on in vitro findings and we cannot be certain if a similar response occurs in human pregnancy in vivo.
Optimal maternal thyroid hormone concentrations could play a critical role in maintaining a balanced inflammatory response in early pregnancy to prevent fetal immune rejection and promote normal placental development through the regulation of the secretion of critical cytokines and angiogenic growth factors by human decidual cells. Our data suggest that there is an ontogenically determined regulatory 'switch' in T3 responsiveness between the first and second trimesters, and support the notion that the timely and early correction of maternal thyroid dysfunction is critical in influencing pregnancy outcomes.
This study is funded by Wellbeing of Women (RG/1082/09 to S.Y.C., M.D.K., J.A.F., L.S.L., G.E.L.) and Action Medical Research - Henry Smith Charity (SP4335 to M.D.K., S.Y.C., L.S.L., J.A.F.). The authors have no conflicts of interest to disclose.
Available from: Ata Mehmet Topcuoglu
- "Th ere are many studies with confl icting results in the literature about the possible association of hypothyroidism and positive thyroid autoantibodies as a risk factor for infertility and 1st trimester miscarriage (Abalovich et al. 2002; Negro et al. 2010; "
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ABSTRACT: Prevalence of abnormalities in thyroid hormones and thyroid autoantibodies in patients with a history of early pregnancy loss (EPL) (n = 17) and unexplained infertility (UI) (n = 25), were compared with that of 45 control patients. TSH, antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-TG) antibody levels in UI and EPL groups were similar to that of the control group. TSH was normal in 39, 22 and 13 of control, UI and EPL patients, respectively. Among patients with a normal TSH, fT4 was higher (p < 0.001) and fT3 was lower (p < 0.001) in infertile patients when compared with the control group. Thyroid function tests seem to be associated with infertility but their association with EPL is weaker. Infertility seems to be associated with a high fT4 and low fT3 status. Thyroid autoantibodies do not seem to be associated with either infertility or EPL.
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