| Objective:Recently, more and more attention have been paid to the impact of maternal thyroid hormones on neuropsychological development of their offsprings. Due to the effect of estrogen and human chorionic gonadotropin (hCG) during pregnancy, the concentration of thyroid hormones among pregnant women are obviously different from the non-pregnant women. And the level of thyroid hormones have changed during the whole gestation. Therefore, it is important to establish the trimester-specific reference intervals for evaluating the concentration and thyroid status among pregnant women. The trimester-specific reference intervals for diagnosis thyroid dysfunction of women during pregnancy created by Yan (Yan’s criteria) is the new one. The purposes of this study, firstly, to understand and appraise the differences and reliability of Yan’s criteria during three pregnant trimesters, compared with the population-based reference intervals (Adults’ criteria). Secondly, Yan’s criteria was used to evaluate the status of thyroid. We explore the impact of maternal subclinical thyroid dysfunction among gestration on brain development of offsprings, which involve in subclinical hypothyroidism and hypothyroxinemia.Method:Pregnant women who live at BAICHENG and WUSHI in Aksu of XINJIANG were selected. The concentration of thyroid stimulating hormone (TSH), free thyroxin (FT4), free triiodothyronine (FT3), total thyroxine (TT4) and total triiodothyronine (TT3) were detected by ICMA. Both Yan’s and Adults’criteria were applied to diagnosis thyroid dysfunction. Total samples of pregnant women are181during the1st trimester,373during2nd and339during3rd trimester. Consistency rate and Kappa value were calculated to evaluate the validity and reliability of Yan’s criterion compared with Adults’criteria. The groups of subclinical hypothyroidism and hypothyroxinemia were studied compared with the control group by means of Yan’s and Adults’criterias. And the offsprings of the pregnancy were administrated with DDST. According to the result of DDST, we divided the infants of that areas into two groups (delay and control Group), and compared the maternal levels of thyroid hormones between the two groups. The statistic methods included Student-test, ANOVA and Chi-squre test, and the statistc software is SPSS11.5. We use0.05as the cut-point of significance.Result:The median concentration of TSH concentration is significantly lower in the1st trimester (M=1.72mIU/L) than that in the2nd (M=2.27mIU/L) and3rd trimester(M=2.38mIU/L) of pregnancy (P<0.001). However, the differences between the2nd and3rd trimester are not significant (P>0.05). The serum level of TSH concentration is significantly higher in the1st trimester (14.24±1.94)pmol/L than that in the2nd (13.36±1.67)pmol/L and3rd trimester (13.49±1.73)pmol/L of pregnancy (P<0.001). But the differences between the2nd and3rd trimester are also not significant (P>0.05). The prevalence of subclinical hypothyroidism diagnosed by Yan’s criteria in the three trimesters are6.6%,9.4%and13.9%, respectively. The prevalence by Adults’ criteria are3.9%,7.2%and9.7%. The differences between the two criterias are significant in2nd and3rd trimester (P<0.05). The prevalence of hypothyroxinemia diagnosed by Yan’s criteria in the three trimesters are6.6%,3.0%and0.0%, respectively. The prevalence by Adults’ criteria are5.0%,12.3%and12.7%. The differences between the two criterias are also significant in2nd and3rd trimester (P<0.001). The result shows that the diagnosis consistency used Yan’s criteria for the same pregnant woman in the adjacent two trimesters is higher than that used Adults’criteria. In the first two trimesters, delay ratio of infants whose mothers belong to subclinical hypothyroidism group (31.2%) is significantly higher than that of control group (13.5%)(P=0.049). Delay ratio of infants whose mothers belong to hypothyroxinemia group (26.7%) is also higher than that of control group. But the differences between the two groups are not significant (P=0.224). In the last trimesters, compared delay ratio of subclinical hypothyroidism group with control group, the differences them are not significant (P>0.05). The same result is showed between hypothyroxinemia group and control group. In2nd trimester, the median concentration of maternal TSH of delay group (M=2.58mIU/L) is significantly higher than that of control group (M=2.29mIU/L). But in the same trimester, the concentration of maternal FT4of the two group are (13.28±1.64) pmol/L and (13.13±1.40) pmol/L, and the differences between them are not significant (P=0.532). Conclusion:Maternal subclinical hypothyroidism in the first two trimesters maybe associated with mental development of offsprings, using Yan’s criteria as references intervals of thyroid hormones for pregnancy. The increasing concentration of TSH is probably valubal to predict the possibility of mental development retardation. The rates of missed diagnosis of subclinical hypothyroidism and misdiagnosis of hypothyroxinemia among pregnant women are decreased due to the application of Yan’s criteria. Yan’s criteria could be more validity and reliability than Adults’criteria during the three pregnant trimesters, and demonstrated more valuable in clinical practice. We confirm the trend of manternal thyroid hormones during the whole gestation., The concentration of TSH during the first trimester is lower than that during2nd and3rd trimester. The concentration of FT4during the first trimester is higher than that during2nd and3rd trimester. |
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