Effects of Autoimmune Thyroiditis on Pregnancy Outcomes: Analysis of the Nationwide Inpatient Sample, 2016-2020

To assess whether autoimmune thyroiditis is associated with obstetric, perinatal, and fetal complications in a nationally representative population of pregnant women.

This retrospective study utilized data from the U.S. Nationwide Inpatient Sample (NIS) and included women aged ≥ 18 years with delivery-related hospitalizations between 2016 and 2020. Patients were categorized based on the presence/absence of autoimmune thyroiditis. Propensity score matching was applied to balance baseline characteristics. Associations between autoimmune thyroiditis and adverse outcomes were assessed using multivariable logistic regression analysis.

Among 3.76 million delivery-related hospitalizations, 17 716 were included. Autoimmune thyroiditis was independently associated with increased risk of gestational diabetes (adjusted odds ratio [aOR] = 1.10, 95% CI: 1.01-1.20), preeclampsia (aOR = 1.22, 95% CI: 1.08-1.38), induction of labor (aOR = 1.18, 95% CI: 1.09-1.26), failed induction of labor (aOR = 1.36, 95% CI: 1.07-1.72), abnormal fetal heart rate or rhythm (aOR = 1.15, 95% CI: 1.06-1.25), and fetal growth restriction (aOR = 1.33, 95% CI: 1.12-1.59). Associations were more pronounced in women younger than 35 years.

Autoimmune thyroiditis is associated with modest increases in adverse pregnancy risk and may inform risk assessment and individualized clinical monitoring.