Positive Impact of Levothyroxine Treatment on Pregnancy Outcome in Euthyroid Women with Thyroid Autoimmunity Affected by Recurrent Miscarriage

Abstract

Impaired thyroid hormone availability during early pregnancy is associated with recurrent miscarriage (RM) and adverse pregnancy outcomes. The main cause of thyroid dysfunction is thyroid-related autoimmunity (TAI), characterized by a significantly higher serum level of thyroid-stimulating hormone (TSH) compared to that of women without thyroid autoimmunity. TAI is associated with a significantly increased risk of miscarriage, and the incidence of TAI in women experiencing RM is higher compared to normal fertile women. In the present study, we have performed a retrospective analysis comparing the ability to conceive, the number of miscarriages and full-term pregnancies between 227 euthyroid women with autoimmune thyroid disease affected by RM and treated with levothyroxine (LT4) as adjuvant therapy, and a control group of 230 untreated women. We have observed a significant improvement of full-term pregnancies in treated women (59%) compared to untreated women (13%, p < 0.0001). Compared to the control group, treated women had a lower percentage of miscarriages (12% vs. 30%) and improved capacity to conceive (57% vs. 29%). Using age as a variable, the outcome in women younger than 35 years was not influenced by the LT4 therapy. Whereas, in women over 35 years, supplementation with LT4 significantly reduced the miscarriage rate (p < 0.05). We can conclude that a transient impairment of TH availability, not easily detectable before pregnancy, could be an important cause of RM in a subset of euthyroid women with autoimmune thyroid disease. This transient impairment may be reverted using adjuvant treatment with low doses of LT4.

Positive effects of thyroid replacement therapy on assisted reproductive technology outcomes in women with subclinical hypothyroidism with positive thyroid peroxidase autoantibodies

“…Recent studies suggest that thyroid autoimmunity may adversely impact pregnancy outcomes ( 22 , 23 ). Although the adverse effects of antithyroid antibodies have been well studied in hypothyroid pregnant women, their effects in euthyroid women and in women with SCl hypoT are not well evaluated.…”

Placental Dysfunction in Assisted Reproductive Pregnancies: Perinatal, Neonatal and Adult Life Outcomes

“…It has been recently demonstrated that TH regulates protease expression and activation of Notch signaling in implantation and embryo development [ 70 ]. Moreover, levothyroxine (LT4) treatment has a positive effect on conception capacity and reduces miscarriages when administered to euthyroid women with autoimmune thyroid disease affected by recurrent miscarriages [ 71 ].…”

The Significance of Trimester-Specific Thyroid Hormones Reference Intervals in Iraqi Pregnant Women

“…[6][7][8][9][10] Regarding thyroid autoantibodies, such as thyroid peroxidase antibody (TPO-Ab) and thy-roglobulin antibody (Tg-Ab), most available research indicates that the high serum level of these antibodies is associated with the increased rate of recurrent abortions and preterm birth. [11][12][13] At the same time, the prevalence of gestational subclinical hyperthyroidism is around 1.7% and usually not associated with any significant adverse pregnancy outcomes. 14 Profound maternal thyroid physiological changes occur during pregnancy.…”