ABSTRACT
Objective To understand the variation of thyroid hormones in each trimesters of pregnancy in women.Methods A total of 1 839 pregnant women in different trimesters were enrolled and thyroid hormones including FT3,FT4,TT3, TT4,TSH,TGAb and TPOAb were measured.The reference range of hormone in each trimester was calculated.Results There were statistically differences in all thyroid hormones among all trimesters of pregnancy women (P<0.05 )except for TT4 between the early and middle trimesters (P>0.05 ).The median of FT3 and FT4 were gradually reduced as the pregnant trimester grew up while the median of TSH had the adverse tendency.The median of TT3 was highest during the middle trimester (1.47 nmol/L).TT4 median was lowest during the late trimester (80.67 nmol/L).The TSH level of pregnant women over 30 years old was significantly lower than that of below 30 age group during all trimesters(P<0.05 ). There were significant differences in FT4,TT3 and TT4 level among early and middle trimesters among different ages groups(P<0.05 ).The positive rates of TGAb and TPOAb during late trimester (4.74% and 1.63%)were significantly lower than those of early trimester (1 4.40% and 5.56%)and middle trimester (1 4.40% and 5.56%)(P<0.05 ). Conclusion Significant differences of thyroid hormones are found not only in different stages of pregnancy,but also in different ages.Therefore,establishing trimester-specific reference data of thyroid hormones during different pregnency may be important for clinical practice.