Increased levels of transforming growth factor beta-1 (TGF-β1) during postpartum are related to less pronounced increases of anti-thyroid peroxidase compared with the third trimester of pregnancy, suggesting an immunosuppressive role for TGF-β1, according to study findings published in Clinical Endocrinology.
Both thyroid physiology and autoimmunity undergo changes during pregnancy, but how maternal hormones affect thyroid autoantibodies during pregnancy and postpartum has not been thoroughly evaluated. In this prospective study, the investigators assessed a cohort of 93 pregnant women during the 24th and 36th weeks of their pregnancies and the first week postpartum. Thyroid hormones, thyroid-stimulating hormone, anti-thyroid peroxidase, anti-thyroglobulin, estradiol, cortisol, and TGF-β1 were measured during the 3 study time points.
Results showed that serum anti-thyroid peroxidase was greater (P <.05) during the first week postpartum compared with the 24th and 36th weeks of gestation. At 36 weeks, cortisol levels were higher (P <.05) and TGF-β1 levels were lower (P <.05) than at 24 weeks and the first week postpartum, during which cortisol was negatively correlated with anti-thyroglobulin (P <.05). The researchers also noted that TGF-β1 was the best negative and estradiol the best positive predictor of anti-thyroid peroxidase (P <.05) in the first week postpartum.
Of note, a positive correlation was observed between estradiol and cortisol. The postpartum increase in TGF-β1 may have been due to the relative cortisol decrease, indicating that estradiol and cortisol were associated with immunosuppression of thyroid antibodies. “Further studies, including translational research approaches regarding the physiopathologic role of the placenta, are needed to reveal the underlying mechanisms to these findings,” concluded the investigators.
Sakkas EG, Paltoglou G, Linardi A, et al. Associations of maternal estradiol, cortisol and TGF-β1 plasma concentrations with thyroid autoantibodies during pregnancy and postpartum [published online August 27, 2018]. Clin Endocrinol (Oxf). doi:10.1111/cen.13843