Subclinical hypothyroidism and related biochemical entities in pregnancy: implications and management.

Subclinical hypothyroidism (SCH), thyroid autoimmunity and isolated maternal hypothyroxinaemia are diagnoses made on laboratory findings. The two former conditions are commonly identified in the general population, while the term isolated maternal hypothyroxinaemia was developed to highlight potential neurodevelopmental risks in progeny. Each entity has been associated with either obstetric, perinatal and/or child developmental harm in observational studies, although few interventional trials have been performed to guide diagnostic and therapeutic approaches. Once diagnosed, treatment of SCH is recommended by endocrine groups to limit potential risk, given that harm from appropriate therapy is unlikely. Screening for thyroid disorders in pregnancy has traditionally been controversial. Definitive trials are expected to report over coming years and updated consensus guidelines will hopefully resolve this issue.