Thyroid peroxidase antibodies are often associated with an increased risk of miscarriage and preterm births. According to a systemic review of 31 studies involving euthyroid women, a strong association was observed between the presence of thyroid peroxidase antibodies and miscarriage. Many small trials have indicated that such adverse outcomes can be reduced with the use of levothyroxine.
However, insufficient evidence exists to conclusively determine whether levothyroxine decreases adverse pregnancy outcomes in patients with positive thyroid peroxidase antibody. Source: The New England Journal of Medicine
