Infertility and pregnancy loss in euthyroid women with thyroid autoimmunity.

Thyroid autoimmunity is the most prevalent autoimmune state that affects up to 5-20% of women during the age of fertility. Prevalence of thyroid autoimmunity is significantly higher among infertile women, especially when the cause of infertility is endometriosis or polycystic ovary syndrome. Presence of thyroid autoimmunity does not interfere with normal embryo implantation and have been observed comparable pregnancy rates after assisted reproduction techniques in patients with or without thyroid autoimmunity. Instead, the risk of early miscarriage is substantially raised with the presence of thyroid autoimmunity, even if there was a condition of euthyroidism before pregnancy. Furthermore the controlled ovarian hyperstimulation, used as preparation for assisted reproduction techniques, can severely impair thyroid function increasing circulating estrogen levels. Systematic screening for thyroid disorders in women with a female cause of infertility is controversial but might be important to detect thyroid autoimmunity before to use assisted reproduction techniques and to follow-up these parameters in these patients after controlled ovarian hyperstimulation and during pregnancy.