Thyroid disease, defined as hormonal abnormalities or the presence of thyroid antibodies in euthyroid women during pregnancy, is associated with maternal, fetal, and newborn complications.1 The relationship between overt thyroid disease (hypothyroidism or hyperthyroidism) and adverse pregnancy outcomes has been known for decades. However, it has only been in the last 20 years that research has linked subclinical hypothyroidism to miscarriage, preterm delivery, preeclampsia, gestational hypertension, and perinatal mortality. Furthermore, since 1990 an association has been reported between thyroid antibody positivity (thyroid peroxidase antibody, thyroglobulin antibody, or both) in euthyroid women and spontaneous miscarriage, recurrent abortion, and preterm delivery.
Alex Stagnaro-Green. Screening Pregnant Women for Overt Thyroid Disease. JAMA. 2015;313(6):565–566. doi:10.1001/jama.2014.17226