Prevalence and Risk Factors of Thyroid Dysfunction in Pregnant Women During the First Trimester at Da Nang Hospital for Women and Children

Background: Thyroid dysfunction during pregnancy, particularly in the first trimester, poses risks to maternal and fetal health, including neurodevelopmental impairments and obstetric complications. Early detection is critical to mitigate adverse outcomes. Methods: A cross-sectional study was conducted from December 2023 to March 2024 at Da Nang Hospital for Women and Children, involving 282 pregnant women in their first trimester (6–13 weeks). Serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels were measured, with reference ranges of 0.1–4.0 mIU/L for TSH (American Thyroid Association [ATA] 2017) and 0.93–1.71 ng/dL for FT4 (hospital standard). Thyroid dysfunction was classified as clinical/subclinical hypothyroidism, clinical/subclinical hyperthyroidism, or isolated hypothyroxinemia. Risk factors (age, BMI, obstetric history, personal/family thyroid disease history) were analyzed using SPSS 20.0, with chi-square tests, Fisher’s exact test, and odds ratios (OR) at p < 0.05. Results: Thyroid dysfunction prevalence was 15.25% (43/282), with subclinical hyperthyroidism (6.03%), isolated hypothyroxinemia (4.26%), clinical hyperthyroidism (2.84%), subclinical hypothyroidism (2.13%), and clinical hypothyroidism (0.35%). Significant risk factors included personal history of thyroid disease (OR = 6.29, 95% CI: 1.93–20.57, p = 0.004) and family history of thyroid disease (OR = 3.68, 95% CI: 1.36–9.96, p = 0.014). No significant associations were found with age >30 years (p = 0.586), BMI ≥23 kg/m² (p = 0.09), or abnormal obstetric history (p = 0.338). Conclusion: Thyroid dysfunction affects 15.25% of first-trimester pregnant women in Da Nang, with subclinical hyperthyroidism being most common. Personal and family history of thyroid disease are significant risk factors, supporting targeted screening in high-risk groups to improve maternal and fetal outcomes.