Associations between hyperthyroidism and adverse obstetric and neonatal outcomes: A study of a population database including almost 17,000 women with hyperthyroidism

Abstract Objective Large population‐based studies on maternal hyperthyroidism's effect on antepartum, intrapartum, and neonatal complications are few. Most of these studies were small or did not evaluate a broad scope of possible complications. Therefore, a large population‐based cohort study was conducted to study the associations between maternal hyperthyroidism and pregnancy and perinatal complications. Design This is a retrospective population‐based cohort study utilizing data from the Healthcare Cost and Utilization Project‐Nationwide Inpatient Sample over 11 years from 2004 to 2014. Patients 16,984 deliveries to women with hyperthyroidism and 9,079,804 deliveries to mothers who did not suffer of hyperthyroidism. Methods A cohort of all deliveries between 2004 and 2014 inclusively was created. Within this group, all deliveries to women with hyperthyroidism were the study group ( n = 16,984) and the remaining deliveries were categorized as nonhyperthyroidism births and comprised the reference group ( n = 9,079,804). The main outcome measures were pregnancy and perinatal complications. Results Maternal hyperthyroidism was associated with several pregnancy and perinatal complications, including increased risks of gestational hypertension (adjusted odds ratio [aOR]: 1.236, 95% confidence interval [CI]: 1.045–1.462, p = .013) and preeclampsia (aOR: 1.190, 95% CI: 1.006–1.408, p = .042). These patients are more likely to experience preterm premature rupture of membranes (aOR: 1.322, 95% CI: 1.007–1.735, p = .044), preterm delivery (aOR: 1.287 95% CI: 1.132–1.465, p < .001), placental previa (aOR: 1.527, 95% CI: 1.082–2.155, p = .016), and suffer from venous thromboembolism (aOR: 2.894, 95% CI: 1.293–6.475, p = .010). As for neonatal outcomes, small for gestational age and stillbirth were more likely to occur in the offspring of women with hyperthyroidism (aOR: 1.688, 95% CI: 1.437–1.984, p < .001 and aOR: 1.647, 95% CI: 1.109–2.447, p = .013, respectively). Conclusions Women with hyperthyroidism are more likely to experience pregnancy, delivery, and neonatal complications. We found an association between hyperthyroidism and hypertensive disorders, preterm delivery, and intrauterine fetal death.