Changes Of Thyroid Function Effect On Outcomes Of Pregnancy And Expression Of Iodothyronine Deiodinase

Changes of the function of maternal thyroid and autoimmunity may lead to several obstertrical complications, and effect on both mother and fetus. Recently, people pay more and more attention to it. However, it is still a question whether it should be a routine screening to examine the thyroid function and antibodies in pregnancy.In this study, we evaluate 632 pregnant women who were for prenatal checked up in our hospital during the period from March,2006 to Feb,2007. All of them had no thyroid disease history. Serum free triiodothyronine (FT3), free thyronine (FT4), thyrotropin (TSH) and thyroid peroxidase antibody (TPOAb) were measured and obstetric outcomes were evaluated in all of the pregnancy women. some of them detected the iodothyrine deiodinase.Our results show that the concentration of FT3 and FT4 decreased with the gestational weeks. The prevalence of clinical and subclinical thyroid diseases was 11.87%, one pregnancy woman (0.16%) had subclinical hyperthyroidism, 43 (6.80%) had subclinical hypothyroidism, 12 (1.90%) had clinical hypothyroidism and 19 (3.01%) had hypothyroxinemia; the prevalence of TPOAb positive was 7.75%. The prevalence of fetal distress was 11.63% in subclinical hypothyroidism, and prevalence of intrauterine growth retardation (IUGR) was 10.53% in hypothyroxinemia group. The prevalence of both groups were much higher than that of the normal group. The prevalence of IUGR in those TPOAb positive was also higher than that of negative. In women who had fetal distress, their TSH level was higher than that of those who had no complication. In women who prematured, their TSH levels were decreased. The level of iodothyrine deiodinase (D2 or D3) on uterus-placenta unit was measured by RT-PCR. Pregnancies whose hypothyroidism was bad controlled, D2 was higher expressed and D3 was lower expressed, compared with those normal and well controlled. Our results suggest that abnormality of the thyroid function and autoimmunity could lead to several obstetric complications. Iodothyronine deiodinase on uterus-placenta unit might relate to regulate maternal-to-fetal thyroid hormones transfer during pregnancy. It is necessary to screen the thyroid function and autoimmunity at pregnancy to find those who are suffered from clinical, especially, subclinial thyroid disease and treat them in time, which might improve the pregnancy outcome.