Effect of levothyroxine treatment on in vitro fertilization and pregnancy outcome in infertile women with subclinical hypothyroidism undergoing in vitro fertilization/intracytoplasmic sperm injection

Objective: To investigate whether levothyroxine (LT4) treatment has beneficial effects on IVF results and pregnancy outcome in infertile patients with subclinical hypothyroidism undergoing IVF/ intracytoplasmic sperm injection (ICSI). Design: Prospective, randomized trial. Setting: University-affiliated infertility clinic. Patient(s): A total of 64 infertile patients with subclinical hypothyroidism, defined as an elevated serum TSH level associated with a normal free T4 level and without frank symptoms of hypothyroidism. Intervention(s): Patients were randomized into an LT4 treatment group or control group. For the LT4 treatment group, 50 mg LT4 was administered from the first day of controlled ovarian stimulation for IVF/ ICSI. Main Outcome Measure(s): Results of IVF and pregnancy outcome. Result(s): There were no differences in patient characteristics between the two groups. Total dose and days of recombinant human FSH used for controlled ovarian stimulation were also similar. The number of grade I or II embryos was significantly higher in the LT4 treatment group than in the control group. There was no significant difference in the clinical pregnancy rate per cycle between the two groups. However, the miscarriage rate was significantly lower in the LT4 treatment group than in the control group. Embryo implantation rate and live birth rate were significantly higher in the LT4 treatment group. In the control group, both thyroid peroxidase antibody and thyroglobulin antibody levels were significantly higher in the miscarried subgroup than in the delivered subgroup. Conclusion(s): LT4 treatment can improve embryo quality and pregnancy outcome in subclinical hypothyroid women undergoing IVF/ ICSI. (Fertil Steril (R) 2011;95:1650-4. (C) 2011 by American Society for Reproductive Medicine.)