Thyroid antibody titer and avidity in patients with recurrent miscarriage

Objective: To determine whether the titer and avidity of the thyroid peroxi dase antibody differs between pregnant women in their first trimester who h ave a history of recurrent miscarriage and whose pregnancies continue to te rm and those whose pregnancies fail again later in the first trimester. Design: Controlled clinical study. Setting: Healthy volunteers in an academic research environment. Patient(s): Pregnant. women in their first trimester who had a history of r ecurrent miscarriage (greater than or equal to 3 miscarriages) and who were known to be positive for the thyroid peroxidase antibody. Intervention(s): None of the patients received any medication. Main Outcome Measure(s): Thyroid peroxidase antibody titer and avidity (i.e ., the net binding strength between antibody and antigen). Result(s): At the time of presentation, thyroid peroxidase antibody titer a nd avidity was significantly higher in those women who later miscarried com pared with those whose pregnancies continued. In those whose pregnancies co ntinued to term, titer and avidity declined as the pregnancy progressed. Conclusion(s): Autoimmunity plays a role in recurrent miscarriage. Among a group of patients who had had recurrent miscarriages, there appeared to be differences in the humoral response to the pregnancy between those whose pr egnancies continued to term and those whose pregnancies failed again. (Fert il Steril(R) 1999;71: 558-61. (C) 1999 by American Society for Reproductive Medicine.)