The impact of maternal overt hypothyroidism during pregnancy on maternal and neonatal outcomes: a case-control retrospective study

Background: Overt maternal hypothyroidism is a common endocrine disorder that can significantly affect the health of both the mother and the fetus during pregnancy. Objective:This study aimed to investigate the impact of maternal hypothyroidism during pregnancy on maternal and neonatal outcomes. Subjects and Methods: This retrospective case-control study was conducted at Fatemieh Educational and Medical Hospital in Hamadan, Iran. Medical records of pregnant women who delivered between 2013 and 2023 were reviewed. Data extraction and analysis were performed between August 2023 and February 2025. Medical records from the past ten years were reviewed, including 3,000 pregnant women—1,500 diagnosed with overt hypothyroidism and 1,500 without the condition. Relevant data were extracted and recorded using a structured questionnaire. Results: Significant differences were observed between the hypothyroid and control groups. Women in the hypothyroid group had a significantly higher risk of adverse maternal and neonatal outcomes. The risk of neonatal respiratory distress was markedly increased in the hypothyroid group (OR = 4.30, 95% CI: 2.41–7.69, p < 0.001). Similarly, the odds of stillbirth were significantly higher (OR = 2.53, 95% CI: 1.91–3.33, p < 0.001). Hypothyroidism was also associated with an increased risk of neonatal hypothyroidism (OR = 3.98, 95% CI: 2.44–6.51, p < 0.001), postpartum hemorrhage (OR = 3.33, 95% CI: 1.81–6.11, p < 0.001), placental abruption (OR = 4.40, 95% CI: 2.49–7.76, p < 0.001), and low birth weight (OR = 3.54, 95% CI: 1.94–6.44, p < 0.001). Additionally, the likelihood of preterm birth was significantly higher in the hypothyroid group (OR = 2.34, 95% CI: 1.37–4.00, p = 0.002). Several comorbidities, including hypertension and combined diabetes with preeclampsia, further increased the risk of adverse outcomes. Conclusion: The findings indicate that overt hypothyroidism during pregnancy increases the risk of complications such as preterm labor, stillbirth, cesarean delivery, placental abruption, postpartum hemorrhage, low birth weight, meconium passage, neonatal hypothyroidism, and respiratory distress syndrome in newborns. Given the relatively high prevalence of this condition among pregnant women, early screening, accurate diagnosis, and timely management are essential to reduce the risk of adverse outcomes. Keywords: Overt hypothyroidism; maternal outcomes; neonatal outcomes; newborn; pregnancy