Thyroid autoimmunity and abortion: a prospective study in women undergoingin vitro fertilization

Objective: To determine whether an association exists between the presence of thyroid peroxidase (TPO) antibodies before pregnancy and miscarriage in women without a history of habitual abortion. Design: Prospective study and nested case-control study. Setting: Inner-city teaching hospital. Patient(s): Four hundred eighty-nine women in an IVF program. Intervention(s): In the prospective study, we measured levels of TPO antibo dies and TSH. in the nested case-control study, we also measured levels of anticardiolipin antibodies. Main Outcome Measure: Miscarriage. Result(s): One hundred seventy-three women were observed, of whom 31% (53/1 73) became pregnant. Pregnancy occurred in 48% (12/25) of the antibody-posi tive women and in 28% (42/148) of the antibody-negative women. Among those who became pregnant, miscarriage occurred in 33% (4/12) of TPO antibody-pos itive women and in 19% (8/42) of TPO antibody-negative women. The TSH level was abnormal (<0.2 mu IU/mL) in only one of the TPO antibody-positive wome n who miscarried. The presence of anticardiolipin antibodies was not associ ated with miscarriage. Conclusion(s): No association was found between the presence of TPO antibod ies before pregnancy and miscarriage in women without a history of habitual abortion. The presence of TPO antibodies did not adversely affect a woman' s chances of becoming pregnant. (C) 1998 by American Society for Reproducti ve Medicine.