Analysis of detection results of thyroid function-related indexes in pregnant women and establishment of the reference interval

Detection results of free thyroxine (FT4), thyroid stimulating hormone (TSH) and thyroid peroxidase antibody (TPOAb) in pregnant women in Linyi region were investigated. A total of 22,235 healthy pregnant women admitted to Women and Children's Health Care Hospital of Linyi from October 2016 to October 2017 were selected and divided into the first-trimester, second-trimester and third-trimester pregnancy groups. Non-pregnant women in the same period were selected as the control group. Roche E601 electrochemiluminescence apparatus was applied to detect FT4, TSH and TPOAb, and statistical analysis was then carried out for the detected data. The positive rate in the third trimester of pregnancy was obviously higher than those in the first and second trimesters of pregnancy (P<0.05). With the prolongation of pregnancy, the reference interval of FT4 was gradually decreased, among which the intervals in the second and third trimesters of pregnancy were significantly lower than those in the non-pregnancy (P<0.05). With the prolongation of pregnancy, the interval in the first trimester of pregnancy was markedly smaller than that in the non-pregnancy group. With the increase of age, the levels of FT4 and TSH tended to be reduced, but the TSH level was increased to a certain degree in patients aged over 40 years. There were differences in the FT4 and TSH reference intervals during pregnancy in comparison among different regions and different detection methods. Region-specific reference intervals need to be established for different trimesters of pregnancy and different detection methods, which is conducive to accurate clinical judgment of thyroid function during pregnancy. TPOAb monitoring needs to be strengthened in the third trimester of pregnancy, and attention should be paid to the changes in thyroid function in pregnant women aged over 40 years.