Discussion
Association between abnormal thyroid function and adverse outcome of pregnancy and maternal health has been widely reported. Thyroid hormone is indeed essential for metabolism and development of the fetus especially in the early time of pregnancy when there is development of neural system. Since the synthesis of thyroid hormone by the fetus begins in the second trimester of pregnancy, it is totally dependent on maternal thyroid hormones in the first trimester. Therefore, any abnormalities of maternal thyroid hormone during pregnancy especially in the first trimester may affect not the development of the fetus but also the postpartum maternal health. There is epidemiologic data about abnormal thyroid function of pregnant women from many countries but this kind of data is limited in Thailand and other south East Asian countries. Abnormal thyroid function is common among thai pregnancies compare to the data from other countries. The prevalence of abnormal TPO-Ab level in thai pregnancies was 13.96% which is close to the data from Turkey (12%), Russian (13.8%), Pakistan (11.2%), bus lower than that the United States (19%) There was no correlation between TPO-Ab, maternal age and gestational age.
Elevation of TPO-Ab can exert the adverse effects even when the mother is euthyroid in the early pregnancy. Although it is not fully understood how thyroid autoantibody interferes with normal pregnancy but the presence of TPO-Ab during the first trimester of pregnancy can increase a chance of developing postpartum thyroiditis about 70%. Once they had a postpartum thyroiditis, there are increased risk for develop permanent hypothyroid in the next 5-10 years
The prevalence of abnormal TSH level in our population is 9.79% in our population is 9.79% in our study the abnormal TSH level was mostly present in the first trimester of pregnancy, same as the recent study from Japan and Russian. Most of abnormality of TSH level found here is slightly low which reflects the occult or mild maternal hyperthyroidism. The normal physiology of pregnancy may be an explanation of this finding. In the first trimester of pregnancy, there are number of important physiological and hormonal and hormone change including increased human chorionic gonadotropin (hCG). Since hCG and TSH share identical alpha subunits and have similar beta subunits and receptors, hCG can weakly turn on thyroid hormone synthesis which results in slightly low levels of TSH in first trimester and return to normal level throughout the duration of pregnancy. To ensure this hypothesis, the dynamic change of TSH during each trimester of pregnancy must be further evaluated. The limitation of this study was the cross-sectional design so comparison of TSH levels of all trimesters of the same pregnant woman cannot be done. However , there was some interesting point about the association between TSH level and presence of TPO-Ab. We found that THS level was significantly higher in the presence of TPO-Ab. This may indicate the subclinical hypothyroid in these mothers. However, there were the pregnant women who had TPO-Ab without abnormalities of TSH. Both groups should be followed for the pregnancy outcomes and postpartum maternal health to determine the clinical significance of TPO-Ab and TSH
Since the prevalence of TPO-Ab and abnormal TSH are common in Thai pregnancies, appropriate guideline for screening the abnormality of maternal thyroid function function during pregnancy especially in the early gestational age should be established in order to reduce morbidity and mortality due to thyroid disease in both mother and child.
Discussion
Association between abnormal thyroid function and adverse outcome of pregnancy and maternal health has been widely reported. Thyroid hormone is indeed essential for metabolism and development of the fetus especially in the early time of pregnancy when there is development of neural system. Since the synthesis of thyroid hormone by the fetus begins in the second trimester of pregnancy, it is totally dependent on maternal thyroid hormones in the first trimester. Therefore, any abnormalities of maternal thyroid hormone during pregnancy especially in the first trimester may affect not the development of the fetus but also the postpartum maternal health. There is epidemiologic data about abnormal thyroid function of pregnant women from many countries but this kind of data is limited in Thailand and other south East Asian countries. Abnormal thyroid function is common among thai pregnancies compare to the data from other countries. The prevalence of abnormal TPO-Ab level in thai pregnancies was 13.96% which is close to the data from Turkey (12%), Russian (13.8%), Pakistan (11.2%), bus lower than that the United States (19%) There was no correlation between TPO-Ab, maternal age and gestational age.
Elevation of TPO-Ab can exert the adverse effects even when the mother is euthyroid in the early pregnancy. Although it is not fully understood how thyroid autoantibody interferes with normal pregnancy but the presence of TPO-Ab during the first trimester of pregnancy can increase a chance of developing postpartum thyroiditis about 70%. Once they had a postpartum thyroiditis, there are increased risk for develop permanent hypothyroid in the next 5-10 years
The prevalence of abnormal TSH level in our population is 9.79% in our population is 9.79% in our study the abnormal TSH level was mostly present in the first trimester of pregnancy, same as the recent study from Japan and Russian. Most of abnormality of TSH level found here is slightly low which reflects the occult or mild maternal hyperthyroidism. The normal physiology of pregnancy may be an explanation of this finding. In the first trimester of pregnancy, there are number of important physiological and hormonal and hormone change including increased human chorionic gonadotropin (hCG). Since hCG and TSH share identical alpha subunits and have similar beta subunits and receptors, hCG can weakly turn on thyroid hormone synthesis which results in slightly low levels of TSH in first trimester and return to normal level throughout the duration of pregnancy. To ensure this hypothesis, the dynamic change of TSH during each trimester of pregnancy must be further evaluated. The limitation of this study was the cross-sectional design so comparison of TSH levels of all trimesters of the same pregnant woman cannot be done. However , there was some interesting point about the association between TSH level and presence of TPO-Ab. We found that THS level was significantly higher in the presence of TPO-Ab. This may indicate the subclinical hypothyroid in these mothers. However, there were the pregnant women who had TPO-Ab without abnormalities of TSH. Both groups should be followed for the pregnancy outcomes and postpartum maternal health to determine the clinical significance of TPO-Ab and TSH
Since the prevalence of TPO-Ab and abnormal TSH are common in Thai pregnancies, appropriate guideline for screening the abnormality of maternal thyroid function function during pregnancy especially in the early gestational age should be established in order to reduce morbidity and mortality due to thyroid disease in both mother and child.
การแปล กรุณารอสักครู่..
