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.
Women of childbearing age（18-45 years old）, natural pregnancy, singleton pregnancy.
Measure thyroid related indexes within 8 weeks of pregnancy: TSH 2.5mIU/L-ULRR, FT4 is normal and TPOAb negativity.
Willing to sign an informed consent form.
History of recurrent miscarriage (≥3 times).
Assisted reproduction (artificial insemination, in vitro fertilization and embryo transfer);
Suffer from diseases that seriously affect pregnancy outcome, including hypertension, diabetes, heart disease, liver and kidney dysfunction, etc.
Failure of vital organs.
Yang ZHANG
Lead sponsor
Peking University First Hospital
Sponsor institution
National Research Institute for Family Planning, China
Collaborator
The Fourth Hospital of Shijiazhuang
Collaborator