Levothyroxine treatment in thyroid peroxidase antibody-positive women undergoing assisted reproduction technologies: a prospective study

Hum Reprod. 2005 Jun;20(6):1529-33. doi: 10.1093/humrep/deh843. Epub 2005 May 5.


Background: Infertile women positive for thyroid antibodies suffer from a poor pregnancy/delivery outcome, although conflicting data have been published. Our objective was to investigate if levothyroxine (LT4) exerts any effect on pregnancy and/or delivery rates in thyroid peroxidase antibody (TPOAb)-positive (+) women undergoing assisted reproductive technologies.

Methods: Patients undergoing treatment were screened for TPOAb, thyroid-stimulating hormone (TSH) and free thyroxine (FT4). A total of 72 (15%) out of the 484 euthyroid women selected were TPOAb (+). These 72 patients were randomly divided into two groups: group A (n = 36) underwent LT4 treatment, group B (n = 36) placebo. Group C consisted of 412 women (85%) who were TPOAb negative (-). All patients received controlled ovarian stimulation. The endpoints of treatment were pregnancy rate, miscarriage rate and delivery rate.

Results: No differences in pregnancy rate were observed between the three groups. Miscarriage rate was higher in TPOAb (+) in comparison to TPOAb (-) [relative risk: 2.01 (95% CI = 1.13-3.56), P = 0.028].

Conclusions: The pregnancy rate is not affected either by presence of TPOAb or treatment with LT4. However, TPOAb (+) women show a poorer delivery rate compared to TPOAb (-). LT4 treatment in TPOAb (+) does not affect the delivery rate.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Abortion, Spontaneous / epidemiology
  • Adult
  • Autoantibodies / blood
  • Birth Rate
  • Female
  • Humans
  • Infertility, Female / blood
  • Infertility, Female / diagnosis
  • Infertility, Female / therapy*
  • Iodide Peroxidase / blood*
  • Middle Aged
  • Pregnancy
  • Pregnancy Rate
  • Prospective Studies
  • Reproductive Techniques, Assisted*
  • Thyroid Diseases / drug therapy
  • Thyroid Function Tests
  • Thyrotropin / blood
  • Thyroxine / blood
  • Thyroxine / therapeutic use*


  • Autoantibodies
  • thyroid microsomal antibodies
  • Thyrotropin
  • Iodide Peroxidase
  • Thyroxine