TPO and thyroid gland disorder: The recently published 2017 ATA Guidelines for the Diagnosis and Management of Thyroid Disease in Pregnancy [6] states that the TSH upper reference limits is 4.0 mIU/L for the typical patient early in pregnancy; for those patients with TSH ranging between 2.5–10 mIU/L we should search for TPO Ab to diagnose SCH and to determine the management approach for the patient.