Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Thyroid autoimmunity and preeclampsia risk: new insights from a rat model (127778)

Elliott S Neal 1 , Rebecca L Brady 1 , Jennifer E Outhwaite 1 , Elliott Grainger 1 , David G Simmons 1 , Bhavisha A Bakrania 2 , Karin Borges 1 , James SM Cuffe 1
  1. School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia
  2. Perinatal Research Centre and UQ Centre for Clinical Research, The University of Queensland, Herston, Brisbane, QLD, Australia

Thyroid autoimmunity (TAI) commonly affects women of reproductive age and increases risk of miscarriage and preterm birth. Some studies have reported associations with gestational hypertension and other vascular diseases (1-2), but no study has investigated the cardiovascular impacts of TAI during pregnancy in an animal model.

To induce TAI, female SD rats were immunised with porcine thyroglobulin in adjuvant and provided sodium iodide in drinking water (n=9). Controls received normal water and injections of adjuvant only (n=10, ‘ADJ’) or PBS (n=9, ‘PBS’). Rats were time-mated thereafter and blood pressure assessed by tail-cuff on gestational day (GD) 9-10 and GD19. Rats were killed on GD20 and tissues collected. 3-4 rats/group underwent echocardiography prior.

Systolic blood pressure in pregnancy was unaffected by TAI or ADJ, but decreased with advancing gestation (-8%, p(Time)=0.006). Maternal heart weight and left ventricular systolic function was unchanged. Litter size and fetal viability was unaffected. However, whole placental weight increased in TAI rats compared to ADJ (+14%, p=0.003) and PBS (+15%, p=0.004) rats, while placental efficiency was reduced (-12% vs. ADJ, p=0.02; -13% vs. PBS, p=0.009). Placental length was greater, but only compared to PBS rats (+9%, p=0.003). Dissected placental junctional zone weight increased (+24% vs. ADJ, p=0.009; +24% vs. PBS, p=0.008). Labyrinth zone weight appeared greater but only reached statistical significance when compared to PBS rats (+12% vs. PBS, p=0.03; TAI vs. ADJ, p=0.056). No changes occurred to fetal body weight, crown-rump length, or brain-to-body and brain-to-liver weight ratios.

Thyroid autoimmunity increased placental weight and reduced placental efficiency, despite no evidence of maternal hypertension or cardiac dysfunction. These placental changes are likely compensatory to prevent deficits in fetal growth, but may cause poor long-term outcomes in offspring. Other preeclampsia-like changes including proteinuria and a high uterine artery resistance index may still be present and are being investigated.

  1. Xu, Y. et al. (2023). Thyroid autoimmunity and adverse pregnancy outcomes: A multiple center retrospective study. Frontiers in Endocrinology, Volume 14 - 2023. doi:10.3389/fendo.2023.1081851.
  2. Raterman, H. G et al. (2013). Increased progression of carotid intima media thickness in thyroid peroxidase antibodies-positive rheumatoid arthritis patients. European Journal of Endocrinology, 169(6), 751-757. doi:10.1530/eje-13-0394.