Thyroid autoimmunity (TAI) tends to be more common in women consulting for fertility problems. However, any underlying causal mechanism connecting TAI to fertility aspects is yet to be established. Increased levels of anti-thyroid peroxidase abs (TPO-abs) have been defined as the most sensitive marker of TAI and are linked to the risk of (sub) clinical hypothyroidism. Therefore,  most studies investigating the prevalence of TAI in infertile women or any relation between TAI and pregnancy outcomes are based on the presence of TPO-abs  alone and do not consider the impact of thyroglobulin autoantibodies (Tg-abs). Assisted reproductive technology (ART) is often proposed as a treatment option for couples confronted with fertility problems. TAI has been linked to adverse pregnancy outcome with an increased risk of miscarriage and preterm delivery in spontaneous pregnancy as well as in pregnancy after ART. Since the late 1990s numerous studies have been published on the impact of TAI and pre-conception TSH thresholds on the outcome after ART. The outcome of these studies is often conflicting.   Therefore, todays guidelines on the management of TAI in the particular case of ART are based on limited evidence.

The present presentation we will give an overview on the association of TAI and female infertility. Underlying possible mechanisms that may connect TAI to fertility issues will be discussed. In addition, evidence on the impact of TAI, pre-conception TSH thresholds and possible benefit of levothyroxine treatment on outcome after ART will be reviewed.