title: Serial in utero ultrasonographic measurements of the fetal thyroid: a new complementary tool in the management of maternal hyperthyroidism in pregnancy.
abstract: OBJECTIVE
  Treatment of maternal hyperthyroidism during pregnancy is complicated by the lack of readily available measures of the thyroid status of the fetus. The aim of this study is to describe the use of serial in utero ultrasound measurements of fetal thyroid in patients being treated for Graves' disease in pregnancy.
  
  
  METHODS
  Over a 24-month period, all pregnant women with Graves' disease attending our special Fetal Thyroid Unit were followed. Maternal thyroid status was assessed by thyroid function tests. Fetal thyroid size was measured serially by transvaginal ultrasonography between 14 and 17 weeks of gestation and by abdominal ultrasonography between 18 and 37 weeks of gestation in 20 women with Grave's disease.
  
  
  RESULTS
  In 15 fetuses, thyroid width and circumference were within the 95% confidence interval of the normal population. In five fetuses, thyroid size was above the 95th percentile for gestational age. In three of them, thyroid size decreased concurrently with a decrease in maternal thionamide dosage, reaching normal range. These three fetuses were born euthyroid. In two fetuses, thyroid size was unaffected by a decrement in maternal drug dosage. Both had neonatal thyrotoxicosis at birth.
  
  
  CONCLUSIONS
  Serial in utero ultrasonography measuring fetal thyroid size in mothers with Graves' disease can serve as an effective noninvasive tool for the early detection of enlarged fetal thyroid. These findings can be used to monitor the maternal antithyroid drug dosage, thereby preventing intrauterine hypothyroidism in some cases. When a dosage reduction does not cause a decrease in fetal thyroid size, transplacental passage of thyroid-stimulating antibodies causing fetal thyrotoxicosis should be suspected.
authors.affiliation: Institute of Endocrinology, Sheba Medical Center, Tel Hashomer, Sackler School of Medicine, Tel-Aviv, Israel.
authors.forename: Ohad
authors.initials: O
authors.lastname: Cohen
authors.forename: Orit
authors.initials: O
authors.lastname: Pinhas-Hamiel
authors.forename: Eyal
authors.initials: E
authors.lastname: Sivan
authors.forename: Mordechai
authors.initials: M
authors.lastname: Dolitski
authors.forename: Shlomo
authors.initials: S
authors.lastname: Lipitz
authors.forename: Reuwen
authors.initials: R
authors.lastname: Achiron
mesh_terms: D000328:Adult; D013956:Antithyroid Agents / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000196:embryology; D005500:Follow-Up Studies; D005865:Gestational Age; D006042:Goiter / Q000000981:diagnostic imaging* / Q000196:embryology; D006111:Graves Disease / Q000188:drug therapy*; D006801:Humans; D008137:Longitudinal Studies; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D011441:Propylthiouracil / Q000008:administration & dosage / Q000009:adverse effects; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000196:embryology; D016216:Ultrasonography, Prenatal / Q000592:standards*
chemical_list: D013956:Antithyroid Agents; D011441:Propylthiouracil