Abstract

BARREIRA, Joana Filipa et al. Immunological changes and thyroid function during pregnancy and postpartum period. Arq Med [online]. 2015, vol.29, n.2, pp.56-60. ISSN 2183-2447.

Pregnancy is associated with a transient and selective tolerance for paternal alloantigens through local placental and systemic immune mechanisms, influenced by hormonal changes. This state prevents the rejection of the fetus which is a semi-allograft and allows the occurrence of fetal microchimerism. In the postpartum period the immune changes are not immediately reversed, but gradually go back to usual state within 12 months after delivery. There is also a physiological adaptation of thyroid gland to pregnancy, occurring a stimulation of the gland by hCG (Human Chorionic Gonadotrophin) and an inverse correlation between this and TSH (Thyroid Stimulating Hormone); an increase in total T₄ (Thyroxine) and T₃ (Triiodothyronine); an increase in thyroid volume, particularly in areas of inadequate iodine intake; and a state of relative deficiency of iodine. It is recommended a daily intake of 250 µg. There are specific reference ranges for TSH in each trimester. This review article aims to systematize immunological and physiological changes in the thyroid function that occur during pregnancy and the postpartum period.

Keywords : pregnancy; postpartum period; thyroid; immune system; autoimmune thyroid disease.

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