| ObjectiveIodine Deficiency Disorders (IDD) is a series syndromes caused by insufficient synthesis of thyroid hormones due to iodine deficiency (IoD) from embryonic development to adulthood, which is characterized with mental and physical retardation and performance by the widespread disease spectrum, from mild to severe impairments. Brain damage is the main impairment by IoD. The mean IQ of children born after USI, who are living in severe IDD areas, has got12.45points increasing compared with those born before USI. IoD is the most popular preventable factor resulted in MD by which reduces synthesis of thyroid hormone (TH). Many nutrition and environmental factors, including malnutrition, goitrogenic substance and insufficient absorb of vitamin might affect on the thyroxin metabolism, and aggravate IDD. Iron deficiency possibly is one of them. The counties of Baicheng and Wushen, Xinjiang Autonomous Region, were the severest IoD areas in histories. Due to prevention, especially, the implementation of Universal Salt Iodization (USI) since1995, IDD in these two counties has been controlled obviously. However, the finding of children with cretinism born after USI showed that the incidence of IDD is still a problem in Baicheng and Wushi County. This study selects pregnant women during different trimester of pregnancy living in Baicheng and Wushi for evaluating the status of iodine and iron nutrition, and explores the role of iodine and iron deficiency on the thyroid function of pregnant woman. In addition, we follow up the infants whose mother accepted check during pregnancy and evaluate the brain development level of theirs. Furthermore, we explore the relationship between the status of pregnant iodine and iron nutrition and offspring’s mental development. The results of this study will provide important baseline data for future research about the relationship between pregnant women and infants mental development.MethodsUsing cohort study.624pregnant women were selected in Baicheng and Wushi from Oct.2008to May.2009. The samples selected approximately account for73.4%of all pregnant women at the same period. Total of433infants were followed up, whose mother were selected during pregnancy from May,2010to July,2011. The parameters of survey included the iodine concentration in drinking water (WI), and urinary iodine (UI). The other indices involved in TSH, TT3, TT4, FT3, FT4, serum ferritin (SF), serum iron and total iron binding capacity of pregnant women. The trimester-specific reference for thyroid tests in pregnant women by Yan (Yan’s reference) was used to evaluate the status of thyroid function. Direct titration assay for testing the salt iodine, Colorimetric ceric-arsenic assay and Vitriolic ammonium assimilation were used for the determination of UI and water iodine. Use portable Hemoglobin instrument to test pregnant women’hemoglobin(Hb). The psychomotor development of infants was evaluated by Denver Development Screening Test (DDST). SPSS16.0was used to process data.ResultsThe medium of iodine concentration in drinking water was2.33μg/L. The medium of group UI was172.12μg/L, and the proportion of UI<50μg/L was12.5%. Along with the pregnancy development, the median UI of pregnant woman at1st,2nd and3rd trimester among the IoD group were181.44μg/L,106.28μg/L and114.16μg/L respectively. The median TSH was2.29mlU/L and the mean of FT4was13.63±1.80pmol/L among all pregnant women.5.0%and15.5%among pregnant women were diagnosed as hypothyroxinemia and subclinical hypothyroidism, respectively. The incidence of anemia, iron deficiency and iron deficient anemia (IDA) were24.6%,37.6%and12.3%respectively.Along with the development of pregnancy, the incidence of subclinical hypothyroidism increased, however, the incidence of hypothyroxinemia decreased with the significant statistic difference among the groups (P<0.05). The TSH, TT3, TT4, FT3and FT4of pregnant women among IoD group had no any statistic difference compared with control group (P>0.05). According to criterion adjusted by the altitude factor (4g/L increase per1000meters), the incidence of anemia, iron deficiency and IDA respectively were30.5%,34.8%and15.2%respectively. The average FT4of pregnant women among severe iron deficiency+IoD group was higher than that among iron deficiency+IoD and control group (P=0.04),20.1%of433infants had been diagnosed as suspicious abnormal with the use of DDST. The suspicious rate of DDST was20.2%among infant whose mother was xposed at risk of ID during pregnancy and19.8%among those whose mother was at risk of iodine sufficiency. The suspicious rate among children whose mother’s SF was lower than criterion during pregnancy was slightly higher than that among normal SF group. The DDST suspicious rate among children whose mother is at risk of iron deficiency without IDA during pregnancy was highest. The analyses of Logistic regression showed that high TSH、low TS and normal Hb, normal SF or SF, and iodine deficiency of pregnant women were the risk factors of suspicious abnormal of brain development among their infants with statistic significance at the0.05level of a.Conclusion1. Pregnant women could be at risk of iodine and iron deficiency, especially during the2nd and3rd trimester. Due to severe IoD environment, the brain development of infant could be impaired. It is still very important to implement iodine supplement.2. Thyroid function and status among pregnancy women is obviously affected by gestation. Trimester, iron deficiency might influence on the condition of pregnant thyroid function to some degree. Moreover, the interaction of IoD and iron deficiency might result in the trend of subclinical hypothyroidism Along with the development of pregnancy, the incident of subclinical hypothyroidism increases and incidence of hypothyroxinaemia decreases, which were evaluated by Yan’s reference.3. The negative of mild iodine deficiency influences on thyroid hormone. However, the other factors related to TH could be considered for pregnant women whose UI exists in the range of100μg/L-150μg/L.4. Higher value of TSH, Lower of transferrin saturation and serum ferritin, and the interaction of serum ferritin and iodine deficiency of pregnant women during gestation were the risks of suspicious abnormal of brain development among their infants. |
PDF Full Text Request