ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 65 P402 | DOI: 10.1530/endoabs.65.P402

Rates of maternal complications from TRAb positive pregnancies are low, but strongly positive TRAb in later pregnancy is associated with adverse neonatal outcomes

Isabel Huang Doran1, James McFarlane1, John Clark Glasgow1, Eirini Bikou2, Emilomon Inetinbor2, Charleen Lia2, Anna Stears1, Diana Wood3, Katarzyna Gajewska-Knapik2, Amanda Ogilvy-Stuart2, Krishna Chatterjee1 & Carla Moran1

1Institute of Metabolic Science, University of Cambridge, Cambridge, UK; 2Rosie Hospital, Cambridge, UK; 3University of Cambridge, Cambridge, UK

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 (2013–2017).

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).

Table 1 Neonatal outcomes depending on TRAb level in third trimester.
TRAb <1 iU/lTRAb 1-3 iU/lTRAb >3 iU/l
Number of pregnancies42617
Number of live births42617
Fetal thyroid dysfunction005
Congenital defects1 (No ATD)01

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.