Effects of controlled ovarian stimulation on thyroid function during pregnancy†

Area of Science:

• Reproductive Endocrinology
• Thyroidology

Background:

• Controlled ovarian stimulation (COS) is crucial for assisted reproductive technologies.
• Changes in thyrotropin levels post-COS can lead to subclinical hypothyroidism, affecting conception.
• Thyroid function alterations vary based on pre-pregnancy thyroid status, autoimmunity, COS protocols, and timing.

Approach:

• Reviewing recent research on COS effects on thyroid function during pregnancy.
• Investigating the pathophysiological mechanisms linking COS to thyroid changes.
• Examining the roles of estradiol, thyroxine-binding globulin, and human chorionic gonadotropin (hCG).

Key Points:

• Elevated estradiol from COS increases thyroxine-binding globulin, lowering free thyroxine (FT4) and raising TSH.
• hCG may exert direct, opposing effects on FT4 and TSH levels via thyroid cell interaction.
• Women with pre-existing thyroid conditions or autoimmunity are more susceptible to COS-induced subclinical hypothyroidism.

Conclusions:

• The precise mechanisms of COS impact on pregnancy and thyroid function require further elucidation.
• Understanding these interactions is vital for optimizing fertility treatments and pregnancy outcomes.
• Further research is needed to fully clarify the pathophysiological pathways involved.