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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
400
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.
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.
Fourth hospital of Shijiazhuang city
Shijiazhuang, Heibei, China
Rate of fetal loss
* 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.
Time frame: From enrollment to the end of treatment at 40 weeks
Fetal loss rates and reasons within 12 weeks of pregnancy.
Time frame: From enrollment to the end of treatment at 12 weeks
Fetal loss rates and reasons within 24 weeks of pregnancy.
Time frame: From enrollment to the end of treatment at 24 weeks
Fetal loss rates and reasons within 28 weeks of pregnancy.
Time frame: From enrollment to the end of treatment at 28 weeks
Fetal loss rates and reasons within 34 weeks of pregnancy.
Time frame: From enrollment to the end of treatment at 34 weeks
Rate of cesarean section
Time frame: From enrollment to the end of treatment at 40 weeks
Gestational week of delivery
Time frame: From enrollment to the end of treatment at 40 weeks
Number of Participants requiring treatments for preventing miscarriage
Drugs, cervical cerclage, etc.
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of hyperemesis gravidarum
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of gestational diabetes
GDM: 1. FPG≥5.1mmol/L,\<7.0mmol/L during the first prenatal examination 2. During weeks 24-28, if blood glucose was elevated in a 75 g oral glucose tolerance test according to the criteria of International Association of the Diabetes and Pregnancy Study Groups; 0 hour ≥5.1 mmol/L, 1 hour ≥10.0 mmol/L, 2 hours ≥8.5 mmol/L Satisfy any of the above criteria to diagnose GDM
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of hypertensive disorders of pregnancy
Hypertensive disorders of pregnancy include: hypertension during pregnancy, preeclampsia and eclampsia
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of early preterm delivery
28 weeks ≤ gestational week of delivery \<34 weeks;
Time frame: From enrollment to the end of treatment at 34 weeks
Rate of late preterm delivery
34 weeks ≤ delivery gestational week \<37 weeks
Time frame: From enrollment to the end of treatment at 37 weeks
Rate of intrauterine growth restriction
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of abruption of placenta
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of dystocia
Dystocia: fetus delivery is difficult, requiring assisted delivery or cesarean section
Time frame: From enrollment to the end of treatment at 40 weeks
Rate of macrosomia
Macrosomia: the newborn's birth weight \>=4000 g
Time frame: From enrollment to the end of newborn delivery date.
Rate of low birth weight
Low birth weight: the newborn's birth weight \<2500 g
Time frame: From enrollment to the end of newborn delivery date.
Incidence of composite adverse outcomes
The occurrence of one or more of these above events (maternal and fetal) was defined as the occurrence of prenatal composite adverse outcomes.
Time frame: From enrollment to the end of treatment at 40 weeks
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