Thyroid Research Thyroid Research Archive Hyperthyroidism

Thyroid dysfunction in fetuses of mothers with Graves’ disease can be detected by sampling umbilical cord blood

(November 2003)

The background of the study. In pregnant women, Graves’ disease can result in fetal thyroid dysfunction, caused by the transplacental passage of thyrotropin (TSH)-like antibodies (TSH receptor-stimulating antibodies) or of antithyroid drug. This study evaluated a protocol designed to detect thyroid dysfunction in fetuses of mothers with Graves’ disease.

How the study was done. The study subjects were pregnant women with Graves’ disease who had serial measurements of serum TSH, thyroxine (T4), and TSH-like antibodies, and monthly fetal ultrasonography to determine fetal heart rate, growth, and goiter. Umbilical cord blood sampling was advised if the maternal serum TSH-like antibody concentration was very high, or if the fetus had tachycardia, goiter, or growth retardation; TSH and T4 were measured in the fetal serum samples.

The results of the study. During the study period there were 40,000 deliveries at this hospital. Eighteen women had Graves’ disease (1:1700, or 0.06 percent); they delivered 26 infants. Two women had twin pregnancies, two had two pregnancies, and one had four pregnancies. Sixteen women took an antithyroid drug during their pregnancies, and 13 took T4, having been treated with radioiodine-131 earlier. Maternal serum TSH-like antibody values were high during 13 pregnancies in eight women.

There were no indications for umbilical sampling in 12 fetuses, and all the infants were normal at birth. One or more indications were met in 14 fetuses, most often a high maternal serum TSH-like antibody value. Nine mothers consented to the sampling. The results were normal in four fetuses. Two fetuses had hyperthyroidism, and three had hypothyroidism. Their mothers were treated accordingly, and all were normal at birth. The fetuses of the mothers who declined umbilical cord sampling were normal at birth.

The conclusions of the study. Measurements of TSH and thyroxine in serum collected by umbilical cord blood sampling detect thyroid dysfunction in some fetuses whose mothers have Graves’ disease.

The original article. Nachum Z, Rakover Y, Weiner E, Shalev E. Graves’ disease in pregnancy: prospective evaluation of a selective invasive treatment protocol. Am J Obstet Gynecol 2003;189:159-65.