Maternal Autoimmune Thyroid Disease and Fetal Thyroxin
Condition: Pregnancy Complicated by Hyperthyroidism; Hypothyroidism in Pregnancy
MeSH terms: Thyroid Diseases; Hypothyroidism; Hyperthyroidism
Study type: Observational

Summary: 
      The purpose of this trial is to correlate fetal thyroid hormones from fetal cord blood with
      clinical (maternal antithyroid drug dose and antithyroid antibodies) and ultrasound (US)
      parameters of fetal thyroid function from pregnant mothers with autoimmune thyroid disease
      (AITD).
    

Detailed description: 
      Maternal hyperthyroidism in pregnancy is complicated with hypertension, preeclampsia, heart
      failure, thyroid storm, preterm labor and stillbirth, while the fetus suffers from
      intrauterine growth retardation (IUGR), goiter; neonatal prematurity and low birth weight.

      Maternal hypothyroidism is seen in 2 % of pregnancies. Risks are higher for preeclampsia,
      postpartum hemorrhage, miscarriage, stillbirth, preterm birth and lower IQ score.

      Thyroid stimulating hormone (TSH) receptor antibodies, antithyroid drugs and iodine pass to
      the fetus. So the fetus may also become a patient. Monitoring fetal growth, fetal heart rate
      (tachycardia is a late sign of fetal hyperthyroidism), bone maturation and the size of the
      fetal thyroid by ultrasound are important parameters for the assessment of transfer of
      hyperthyroidism from mother to the fetus

      Patients follow up:

      After inclusion into the study, thyroid function tests (fT4, TSH), and auto-antibodies
      assessment (anti TPO, TRAK) were performed once every two months in mothers with AITD, and
      from the 24th week of gestation monthly. Treatment was adjusted accordingly. Ultrasound for
      fetal size, morphology and fetal heart rate (FHR) was performed once in two months, and from
      the 24th week of gestation, monthly. The fetal biophysical profile score was determined
      weekly from the 30th week of gestation. The single centre design was chosen: all fetal
      sonograms were performed by the same gynecologist. Cardiotocography was performed once weekly
      from the 30th week of gestation.

      Study design:

      Fetal and maternal free thyroxin (fT4) and TSH, thyroid antibodies in mothers and fetal
      ultrasound (fetal size, morphology and fetal heart rate) were determined at the same time,
      once, from 22nd to 33rd weeks of gestation.

      Procedure: Cordocentesis (Cordocentesis is a highly specialized prenatal test in which a
      fetal blood sample is removed from the umbilical cord and tested for genetic problems,
      hormones or infections. Cordocentesis can be done at 18 weeks of pregnancy or later). Fetal
      fT4 and TSH were measured from cord blood samples. Healthy pregnant subjects were directed
      for cordocentesis for karyotype analysis due to age (missed previous procedures for
      karyotyping).

      The diagnosis of fetal hypo or hyperthyroidism was established taking into account fT4
      concentrations according to the nomograms Thorpee-Beeston et al., 1996, 1991.

      When fetal hyperthyroidism is diagnosed, antithyroid drugs given to the mother are
      administered or adjusted. When fetal hypothyroidism is diagnosed, then the possibility of
      intraamniotic thyroxin application is discussed with the mother.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Groups are selected from State tertiary referral centre for Gynecology and Obstetrics
      
Keywords: pregnancy; autoimmune thyroid disease; fetal thyroid hormones; antithyroid antibodies; ultrasound parameters