Levothyroxine Intervention in Pregnant Women with TSH （2.5 MIU/L-upper Limit of Reference Range） and Negative Thyroid Peroxidase Antibody

Condition(s) studied

Investigational drug(s) / intervention(s)

Levothyroxine Sodium (LT4) Tablets: Participants in our study will determine the dosage of L-T4 based on their weight (BW): 1. BW ≥50kg: Starting with a daily dose of 1 tablet; 2. BW \< 50kg: Starting with a daily dose of half a tablet. At 12 weeks, 18-20 weeks, 24-26 weeks, and 34-36 weeks of gestation, the serum TSH, FT3, and FT4 will be measured, and investigator will adjust dosage according to TSH: 1. When TSH \> ULRR, the participants will receive L-T4 in addition to their original medication, and additional unplanned follow-up; 2. When TSH at 2.5mIU/L-ULRR, add 1/4 tablet of medictaion; 3. When TSH at LLRR -2.5mIU/L, maintain the original dose; 4. When TSH \<LLRR, reduce 1/4 tablets of medictaion. 5. If TSH continues to be lower than LLRR after discontinuation, investigator will measure FT4, TRAb and other indicators to determine if it is clinical hyperthyroidism. If so, antithyroid drugs will administered according to guidelines. Participants will stop all trial medictaion after delivery.

Placebo: Participants in our study will determine the dosage of placebo based on their weight (BW): 1. BW ≥50kg: Starting with a daily dose of 1 tablet; 2. BW \< 50kg: Starting with a daily dose of half a tablet. At 12 weeks, 18-20 weeks, 24-26 weeks, and 34-36 weeks of gestation, the serum TSH, FT3, and FT4 will be measured, and investigator will adjust dosage according to TSH: 1. When TSH \> ULRR, the participants will receive L-T4 in addition to their original medication, and additional unplanned follow-up; 2. When TSH at 2.5mIU/L-ULRR, add 1/4 tablet of medictaion; 3. When TSH at LLRR -2.5mIU/L, maintain the original dose; 4. When TSH \<LLRR, reduce 1/4 tablets of medictaion. 5. If TSH continues to be lower than LLRR after discontinuation, investigator will measure FT4, TRAb and other indicators to determine if it is clinical hyperthyroidism. If so, antithyroid drugs will administered according to guidelines. Participants will stop all trial medictaion after delivery.

Study summary

The goal of this clinical trial is to learn if levothyroxine (L-T4) works to treat pregnant women with TSH 2.5 mIU/L-the upper limit of reference range (ULRR) of pregnancy and TPOAb-negative. It will also learn about the safety of L-T4. The main quesitons the investigator want to answer are:

* Will L-T4 reduce miscarriage rates and have an impact on pregnancy complications in pregnant participants?
* What medical issues do participants have when taking L-T4 during pregnancy? -Investigators will compare L-T4 with placebo (a substance with a similar appearance without medication) to see if L-T4 could reduce miscarriage rates

Participants should:

* Take L-T4 or placebo during the whole pregnancy.
* Visit the hospital once every 6-8 weeks during pregnancy for checkups and tests
* Keep a diary of their pregncny complications and daily record of L-T4 or placebo intake.
* Visit the hospital for examination 42 days postpartum for checkups and follow up by phone at 6 and 12 months postpartum.

Eligibility

Primary outcome measure(s)

• Rate of fetal loss — From enrollment to the end of treatment at 40 weeks
  * Abortion: Ultrasound examination shows no embryo sac or only empty sac, no fetal heart or bud development. * Intrauterine fetal death: Fetal death in utero at 20 weeks or more of pregnancy. * Stillbirth: Death at birth over 28 weeks of pregnancy. * Neonatal death: Newborns die within 7 days.

Trial sites (1)

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