• Check TSH and request neck ultrasound in women with new or enlarging thyroid nodules in pregnancy.
• Refer to a specialist -  endocrinologist or a thyroid surgeon.
• If the ultrasound shows the nodule might be a cancer, they will be sent for a fine needle aspiration. This is a safe procedure to have in pregnancy.
• Surgery for most common thyroid cancers diagnosed in pregnancy can usually be postponed until after birth unless the cancer is growing quickly, or if it is pressing on the windpipe and causing problems with breathing.
• RAI ablation is contraindicated in pregnancy.
• If surgery is required, this is best performed at 14-22 weeks but new American Thyroid Association (ATA) guideline will recommend any stage.
• Counsel women that there is no difference in the rate of recurrence/long-term survival in well-differentiated thyroid cancers identified in pregnancy compared with those diagnosed outside pregnancy.
• In women with previous thyroid cancer, their TSH target should be the same as outside the pregnancy.
• Thyroglobulin monitoring is difficult as it is affected by pregnancy.
• Ultrasound monitoring in women with suspicious/malignant nodules can be useful where surgery route is not taken.

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