Severe thyroid dysfunction can lead to subfertility via different pathways like altered menstruations, changes in reproductive hormone levels and through a direct impact on the ovaries. Fertility problems may persist even after thyroid function normalization, and require surgery and/or an assisted reproductive technology (ART). Several studies showed that women with polycystic ovarian syndrome and idiopathic subfertility have a higher prevalence of thyroid autoimmunity (TAI) compared with fertile women or women with other subfertility causes.
Prior to ART treatment, ovarian stimulation (OS) is performed, leading to high estradiol levels, in turn potentially resulting in (subclinical) hypothyroidism in women with TAI, requiring thyroid hormone supplements (LT4) before pregnancy. Women with (subclinical) hypothyroidism prior to OS and treated with LT4 should target a serum TSH level <2.5mIU/L.
In meta-analyses including women with TSH levels >4.0mIU//L, LT4 increased live birth rates, but this was not the case in euthyroid women with TAI. However, the use of intracytoplasmic sperm injection seems to be promising in those women.
Based on the above-mentioned reasons, routinely screening for thyroid disorders in women of subfertile couples is strongly advised.
Keywords
Autoimmune thyroiditis, in vitro fertilization, hyperthyroidism, hypothyroidism, subfertility, intracytoplasmic sperm injection, assisted reproductive technology