Abstract:

Objective · To investigate the normal ranges of thyroid function indexes in pregnancy through the positive values of autoimmune antibodies. Methods · 730 pregnant women were recruited. Levels of serum thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) were measured with chemiluminescence immunoassay. The values of each index in the normal ranges were assigned to the respective low, medium, and high groups. The differences in the positive rates of TPOAb and TGAb between groups were analyzed. Results · The differences in the positive rate of TPOAb between TSH low, medium, and high groups in each trimester of pregnancy were statistically significant. Comparison between groups showed that the TSH high group was more likely to develop abnormal TPOAb level than TSH low and medium groups. There was a significant positive correlation between the normal TSH value and the TPOAb positive value in first trimester of pregnancy (r=0.661, P=0.038). Conclusion · The high TSH level in normal range is more likely to be associated with abnormal TPOAb level in each trimester of pregnancy, which provides an idea for determine the normal ranges of thyroid function indexes. Screening and follow-up for thyroid function and autoimmune antibodies of pregnant women should be enhanced to avoid adverse pregnancy outcomes.

Key words: normal reference, thyroid function, pregnancy, autoimmune antibody