Certain groups of women have a higher risk of developing abnormal thyroid function during pregnancy. If you are in one of these ‘at risk’ groups, your doctor should do a blood test to check your thyroid levels in early pregnancy.

Who is at risk?

History of thyroid disease or surgery	Autoimmune conditions with obstetric complication	Previous late pregnancy loss
Previous thyroid surgery	Type 1 diabetes mellitus	Stillbirth
Goitre	Systemic Lupus Erythematosus	Second trimester miscarriage
Thyroid nodule	Anti-Ro/Anti-La positivity
Previous overt or subclinical thyroid dysfunction	Anti-phopholipid syndrome
Previous thyroiditis
Positive TPO antibodies
Previous radioiodine ablation
Taking medication which disrupts thyroid function e.g. lithium, amiodarone
Previous head/neck irradiations
Cardiac dysrhythmia (irrregular heartbeat)
Significant weight loss
Enlarged thyroid gland
Thyroid nodule

Read the RCOG Green-top guideline on the Management of Thyroid Disorders in Pregnancy