Assessment of Prevalence of Hypothyroidism in Pregnancy Visited to Tertiary Care Teaching Hospital: An Observational Study

Abstract

Background: Maternal hypothyroidism, a common endocrine disorder in pregnancy, is associated with significant adverse outcomes for both mother and fetus if undiagnosed. While universal screening remains debated, region-specific prevalence data is crucial for informing clinical practice and policy. Objectives: To assess the prevalence of hypothyroidism among pregnant women attending the tertiary care teaching hospital and to correlate it with maternal age and trimester.

Materials and Methods: A hospital-based cross-sectional study was conducted over six months (January 2019 – June 2019). Seventy-four (74) consecutive pregnant women attending the antenatal clinic, regardless of gestational age, were enrolled. After obtaining informed consent, demographic and clinical data were recorded. Venous blood samples were collected for measurement of Thyroid Stimulating Hormone (TSH) and Free Thyroxine (FT4) using chemiluminescent immunoassay. Diagnosis of hypothyroidism was made as per the American Thyroid Association (ATA) 2017 guidelines: TSH >4.0 mIU/L (or trimester-specific reference ranges where available) and/or low FT4. Overt hypothyroidism (OH) was defined as elevated TSH with low FT4, while subclinical hypothyroidism (SCH) was defined as elevated TSH with normal FT4.

Results: The mean age of participants was 26.4 ± 4.1 years. The overall prevalence of hypothyroidism was 20.3% (15 out of 74). Of these, subclinical hypothyroidism (SCH) was the most common, constituting 73.3% (11/15) of cases, while overt hypothyroidism (OH) constituted 26.7% (4/15). The highest prevalence was observed in the first trimester (33.3%), followed by the second (18.5%) and third (14.8%) trimesters. Women aged >30 years showed a higher prevalence (35.7%) compared to those ≤30 years (16.1%).

Conclusion: The study reveals a high prevalence (20.3%) of hypothyroidism among pregnant women in this setting, with SCH being predominant. This underscores the necessity of targeted case-finding and consideration for universal TSH screening in the first trimester at tertiary care teaching hospital in this region to ensure timely intervention and optimize maternal-fetal health.