PREVALENCE OF SUBCLINICAL HYPOTHYROIDISM IN THE FIRST TRIMESTER OF PREGNANCY AND ITS ASSOCIATION WITH MATERNAL AGE AND PARITY

Abstract

The negative impact of a lack of maternal thyroid hormones on pregnancy outcomes and the intellectual development of offspring has been known for many years. Given the well-known physiological decrease in TSH levels during pregnancy, any elevation in these levels is highly sensitive and indicative of dysfunction. Appropriate screening, diagnosis, and treatment of hypothyroidism during pregnancy are crucial, especially considering the risks to fetal neurocognitive development and obstetric complications caused by improper management.
Objectives: The aim of this study was to determine the prevalence of subclinical hypothyroidism during the first trimester of pregnancy in our population of pregnant women, and its association with maternal age and the number of previous deliveries.
Methods: We conducted a prospective cross-sectional study at the Department of Obstetrics and Gynecology of the Primary Health Care Center Cazin, Bosnia and Herzegovina, during the period from January 1, 2024, to January 1, 2025. A total of 232 pregnant women with recorded serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels in the pregnancy and childbirth database were analyzed. The reference range used for diagnosing subclinical hypothyroidism was a TSH level of 2.5–4.0 mU/L, according to the recommendation of the American Thyroid Association (ATA). Statistical analysis was performed using IBM SPSS statistical software, version 27. Data were analyzed using descriptive statistics, including frequencies, means, and standard deviations.
Results and Discussion: The average TSH value in our sample was 1.78±0.85 mU/L. The mean fT4 values were 10.2±3.87 mU/L. The incidence of subclinical hypothyroidism was more frequent among pregnant women aged 25 to 29 years (9 cases or 3.88%) compared to other age groups, although this difference was not statistically significant. This suggests a trend toward increased prevalence of hypothyroidism with advancing maternal age. A higher incidence of subclinical hypothyroidism was also observed in multigravida patients. The prevalence of subclinical hypothyroidism in our study was 13.4%, while overt hypothyroidism was present in 1.7% of participants. Based on our findings, we recommend universal screening for thyroid disorders in all women, ideally before conception or during their first prenatal visit.
Conclusion: Pregnancy is a state of increased metabolism, which can mask the symptoms of hypothyroidism. Thyroid dysfunction is easily detectable and can be treated effectively and inexpensively, thereby preventing adverse pregnancy outcomes. A comprehensive approach highlights the crucial importance of studying the impact of hypothyroidism on feto-maternal outcomes, emphasizing the vital role of universal screening in improving maternal and neonatal health.In our population of pregnant women, subclinical hypothyroidism was observed in 13.4% of cases, making it more prevalent than overt hypothyroidism, which was present in 1.7% of cases.
Recommendations: Serum TSH and fT4 should be included in the panel of routine tests for the early diagnosis and treatment of thyroid disorders during pregnancy.