Fetuses of Mothers with Thyroid Disease May Be at Higher Risk of Developing Supraventricular Tachycardia

Fetal tachyarrhythmias complicate 0.5% of pregnancies, with high morbidity and mortality. We hypothesized that maternal factors may predispose to fetal supraventricular tachycardia (SVT).

We reviewed medical records of all 124 mothers who presented to the Vanderbilt Fetal Cardiology Clinic from 2004 to 2010 for fetal arrhythmias, excluding heart block. Maternal factors were compared between 28 fetuses with SVT and a control group of 112 fetuses screened for noncardiac conditions. The proportions were analyzed using chi-square or Fisher exact test for categorical variables and Wilcoxon rank sum test for continuous variables.

Of maternal factors, thyroid disease was statistically significant compared with controls. Among mothers whose fetuses had SVT, 21% had thyroid disease (83% hypothyroidism) compared with 3% of controls (p < 0.001).

In this cohort, the maternal thyroid disease was more common in fetuses with SVT compared with controls (odds ratio = 9.8, 95% confidence interval 2.3-42.3), suggesting closer screening for fetal arrhythmias and SVT in mothers with thyroid disease. Also, routine screening of thyroid functions and thyroid autoantibodies may be warranted in mothers of fetuses with SVT.