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Levothyroxine Treatment and IVF Outcomes in Women With Subclinical Hypothyroidism: A Target Trial Emulation

NCT07257250 · Status: RECRUITING · Type: OBSERVATIONAL · Enrollment: 900

Last updated 2026-01-14

No results posted yet for this study

Summary

Subclinical hypothyroidism (SCH) is defined by elevated thyroid-stimulating hormone (TSH) with normal free thyroxine (fT4) levels. It affects approximately 5-7% of women of reproductive age and may negatively influence outcomes of assisted reproductive technology (ART). During controlled ovarian stimulation, rising estradiol increases thyroxine-binding globulin and thyroid hormone requirements. These physiological changes, combined with increased metabolic demand in early pregnancy, may worsen SCH and contribute to adverse outcomes such as miscarriage, preterm birth, and hypertensive disorders of pregnancy.

Although levothyroxine (LT4) is routinely used to treat overt hypothyroidism, evidence for its benefit in SCH, especially among infertile women undergoing In Vitro Fertilization (IVF) or Intra-Cytoplasmic Sperm Injection (ICSI) with frozen embryo transfer (FET), remains inconclusive. Some trials and meta-analyses have shown reductions in miscarriage and neonatal mortality, while others have found no improvement in ART or obstetric outcomes.

This study aims to evaluate the effectiveness of levothyroxine therapy on IVF/FET outcomes and subsequent pregnancy results in women with subclinical hypothyroidism and infertility. This retrospective cohort study will emulate the target trial to evaluate whether LT4 treatment, titrated to achieve a pre-transfer TSH \< 2.5 mIU/L, improves implantation, live birth, and obstetric outcomes compared with expectant management.

Conditions

  • Subclinical Hypothyroidism
  • Infertility
  • Assisted Reproductive Technology
  • In Vitro Fertilization (IVF)
  • Intracytoplasmic Sperm Injection
  • Frozen Embryo Transfer (FET)

Sponsors & Collaborators

  • Mỹ Đức Hospital

    lead OTHER

Eligibility

Min Age
18 Years
Max Age
45 Years
Sex
FEMALE
Healthy Volunteers
No

Timeline & Regulatory

Start
2019-01-01
Primary Completion
2024-12-30
Completion
2026-03-30

Countries

  • Vietnam

Study Locations

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Entities

Diseases

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT07257250 on ClinicalTrials.gov