Thyroxine Therapy for Recurrent Pregnancy Loss in Hypothyroid Women

Abstract

Objective: To estimate the optimal TSH level for starting T4 treatment in subclinical hypothyroidism.

Study Design: Non-randomized clinical trial study

Place and Duration of Study: This study was conducted at the Tertiary Obstetric Hospital at Al-Kindy College of Medicine, Iraq from March 2022 to May 2023.

Methods: It comprised 77 cases. The participants were women with TSH levels above 2.5 mU/L and with RPL. The study had two groups based on thyroid-stimulating hormone (TSH) levels (TSH level 2.5-4 mU/L and TSH ≥4 
mU/L groups). Participants received T4 therapy and were followed for 6 months. The primary outcome was the rate of successful pregnancy, followed until delivery and the gestational age and birth weight of the newborn.

Results: The rate of successful pregnancy, gestational age, and birth weight were not different between the two groups. The titer of thyroid peroxidase antibodies was significantly reduced after 6 months of T4 therapy, but the starting threshold of the treatment did not influence the amount of reduction of the titer. Regression analysis showed, the titer of thyroid peroxidase antibodies after 6 months of treatment was significantly associated with increased rate of successful pregnancy.

Conclusion: Reducing the thyroid-stimulating hormone treatment threshold alone may not guarantee improved pregnancy outcomes. The study suggests that T4 therapy's benefits may be more closely linked to antibody titer changes.