EFFECT OF THYROID DISEASES ON SUBFERTILITY

Abstract

Background: Subfertility refers to a significant reproductive condition that impacts a significant percentage of those women in the world. The thyroid hormones are important in manipulating ovulation, endometrial receptivity, implantation and reproductive functioning in general. Thyroid dysfunction especially hypothyroidism has been increasingly identified as a possible reversible cause of subfertility in women; nevertheless, local data on the effect of thyroid dysfunction is minimal in Pakistan.

Aim: To identify the relationship that exists between thyroid disorders and subfertility in women who visit a tertiary care hospital in Lahore, Pakistan.

Methods: This prospective case-control study was done in the Department of Obstetrics and Gynecology, Gulab Devi Teaching Hospital, Lahore from December 2025 to May 2026. Non-probability consecutive sampling was used to enroll 166 women (83 sub-fertile (cases) and 83 fertile (controls)). Structured interviews were used to collect demographic, clinical and lifestyle data. The chemiluminescent immunoassay of serum thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) was performed. The SPSS version 27 was used to analyze data with p≤0.05 was regarded statistically significant.

Results: The mean serum TSH level was significantly higher among sub-fertile women than fertile controls (4.68 ± 2.29 vs. 2.31 ± 1.04 mIU/L, p<0.001), whereas FT4 (0.93 ± 0.27 vs. 1.26 ± 0.21 ng/dL, p<0.001) and FT3 levels (2.78 ± 0.62 vs. 3.21 ± 0.53 pg/mL, p<0.001) were significantly lower. Subclinical hypothyroidism was found in 25.3% of cases and 8.4% of the controls, whereas overt hypothyroidism was found in 12.0% and 2.4%, respectively. After controlling the confounding factors, women who had thyroid disorders were found to be 5 times more likely to be subfertile (Adjusted OR=5.02, 95% CI: 2.39-10.54, p<0.001). The highest independent predictors of subfertility were elevated TSH (Adjusted OR=6.74, 95% CI: 2.9115.61, p<0.001). Serum TSH levels showed a significant positive relationship with length of subfertility (r=0.481, p<0.001).

Conclusion: Thyroid disease, especially hypothyroidism, was largely related to subfertility and became a predictor of reproductive impairment by itself. A high concentration of TSH and low concentration of thyroid hormone were closely associated with poor fertility rates. Thyroid screening should be part and parcel of infertility screening to ease the process of identifying and treating abnormalities in thyroids.