Impact of Levothyroxine in Miscarriage and Preterm Delivery Rates in First Trimester Thyroid Antibody-Positive Women With TSH Less Than 2.5 mIU/L.

Abstract

Thyroid disease during pregnancy is associated with multiple adverse maternal and fetal outcomes. In particular, multiple observational studies have demonstrated an association between the presence of thyroid antibodies in euthyroid women in the first trimester of miscarriage and an increased rate of spontaneous miscarriage and preterm delivery. The present study is a prospective intervention trial of the effect of levothyroxine on the rate of miscarriage and preterm delivery in euthyroid thyroid-antibody positive women in the first trimester of pregnancy. A total of 8530 women in the first trimester of pregnancy in Southern Italy were screened for TSH and thyroid antibodies. Group A consisted of 198 euthyroid thyroid antibody positive women treated with levothyroxine, group B consisted of 195 untreated euthyroid thyroid antibody positive women, and group C consisted of 197 untreated thyroid antibody negative women. The rate of miscarriage did not differ between the 3 groups (11.6%, 14.9%, and 8.1 %, P = .11). The rate of preterm delivery between the 3 groups was 6.9%, 10.8%, and 2.8% and was statistically significant (P = .01). The rate of preterm delivery was significantly different between groups B and C (P = .02) but was not significantly different between groups A and B (P = .27). In conclusion, the present study found that levothyroxine intervention had no impact on the rate of miscarriage and preterm delivery in euthyroid thyroid antibody positive women.