Introduction: Graves disease during pregnancy may cause maternal or neonatal complications, including arrhythmia, thyroid storm, congenital anomalies and neonatal thyroid dysfunction (TD). The optimal timing and frequency of TRAb measurement in pregnant women with a history of TD, and whether fetal monitoring could be limited to those with a strongly positive TRAb, is unclear.
Methods: Retrospective case note review of women with elevated TRAb (>1 iU/l) during pregnancy at our institution (20132017).
Results: 47 women had a positive TRAb and/or received ATDs during pregnancy. 4/47 women with a negative TRAb in the first trimester developed a positive TRAb (highest 4.5 iU/l) later in pregnancy. 10/47 had a strongly positive TRAb (>3 iu/l) in the first trimester, of whom the majority (n8) had a positive TRAb (>1 iu/l) later in pregnancy. Only one mild congenital anomaly was recorded in those on ATDs (all PTU, n19). Neonatal TD occurred in five babies; necessitating temporary treatment with carbimazole (n1) or thyroxine (n1).
|TRAb <1 iU/l||TRAb 1-3 iU/l||TRAb >3 iU/l|
|Number of pregnancies||4||26||17|
|Number of live births||4||26||17|
|Fetal thyroid dysfunction||0||0||5|
|Congenital defects||1 (No ATD)||0||1|
Conclusions: Almost all with a strongly positive TRAb in the first trimester have a persistently positive TRAb later in pregnancy. Development of a newly positive TRAb in late pregnancy is rare. No adverse maternal outcome during pregnancy was reported, however neonatal thyroid dysfunction occurred in almost 30% of babies born to women with a strongly positive third trimester TRAb. Our findings suggest that early pregnancy TRAb predicts later TRAb levels; and that screening for fetal thyrotoxicosis should be intensified in women with a strongly positive third trimester TRAb.