The background of the study. Autoimmune thyroid disease has been associated with infertility and miscarriage. In this study, pregnancy, miscarriage, and delivery rates were determined in infertile women with autoimmune thyroiditis who were treated with thyroxine (T4) or placebo and then underwent in vitro fertilization. Infertile women who did not have autoimmune thyroiditis also were studied.
How the study was done. The study subjects were 484 infertile women scheduled to undergo their first cycle of in vitro fertilization and embryo transfer to the uterus. Among the 484 women, 72 (15 percent) had a high serum antithyroid peroxidase antibody concentration. They were randomly assigned to receive T4 (1.0 ?g/kg per day) or placebo. One month later, assisted reproduction was begun. T4 therapy was continued throughout any pregnancy.
After stimulation of the ovaries, oocytes were retrieved and fertilized in vitro, and one to three embryos were transferred to the woman’s uterus. Pregnancy was confirmed by high serum chorionic gonadotropin concentrations and ultrasonography. The end points were pregnancy rates, miscarriage rates, and delivery rates.
The results of the study. The mean age, reproductive history, causes of infertility, and serum TSH and T4 concentrations were similar in the three groups of women. The pregnancy rate was also similar in the three groups (53 to 56 percent). Among the women who became pregnant, the miscarriage rate was 25 percent in the women with normal serum antibody concentrations, as compared with 40 and 47 percent in those with high serum antibody concentrations treated with T4 and not treated, respectively. The respective delivery rates were 75, 60, and 53 percent.
The conclusions of the study. The rate of pregnancy in women undergoing in vitro fertilization and embryo transfer is similar in women with and without high serum antithyroid antibody concentrations. The rate of miscarriage is higher in the former group, and among them it is not reduced by T4 treatment.
The original article. Negro R, Mangieri T, Coppola L, Presicce G, Casavola EC, Gismondi R, Locorotondo G, Caroli P, Pezzarossa A, Dazzi D, Hassan H. Levothyroxine treatment in thyroid peroxidase antibody-positive women undergoing assisted reproduction technologies: a prospective study. Hum Reprod 2005;20:1529-33.