Screening for thyroid disease in pregnancy

Diagnosis/definition:

• Normal TSH values in pregnancy: 2.5-4.0 mIU/L
• Normal fT4 values in pregnancy: 0.7-1.8 ng/dL
• Definition of subclinical hypothyroidism: serum TSH 2.5 mIU/L to 10mIU/L, fT4 concentration 0.7 ng/dL to 1.8 ng/dL, and absence of symptoms

Complications:

• Overt maternal hypothyroidism hinders childhood neurodevelopment
• Maternal subclinical hypothyroidism or hypothyroxinemia may be associated with diminished IQ in offspring
• Overt hyperthyroidism complicating pregnancy is associated with increased risk of spontaneous pregnancy loss, congestive heart failure, thyroid storm, preterm birth, preeclampsia, and fetal growth restriction.

Management:

• Routine thyroid screening in pregnancy is not recommended
• Thyroid testing in pregnancy should be conducted for women “at risk,” including known thyroid disease,
• symptoms of overt thyroid disease, suspected goiter, autoimmune medical disorders such as Type 1 diabetes mellitus
• Routine treatment of subclinical hypothyroidism is not recommended
• Routine thyroid testing of women with hyperemesis gravidarum is not recommended

Last Reaffirmed: Aug 1, 2014