| In recent years, infants mortality's causes have changed greatly, birth defects, one of the causes,are weightening increasingly. Neural tube defects had a high incidence, seriously influenced the birth - population diathesis and disabled.Closure of the neural tube is essential for normal development of the brain and spinal cord. Failure of closure during 24 - 28 days of fetus results in neural tube defects ( NTDs). The birth prevalence rate of neural tube defects ( NTDs) of China is among the highest in the world areas. To study the epidemiological features and secular trends and affects of NTDs can apply with a scientific gist of etiology and decreasing the adverse perenatal babies outcome.ObjectiveThe database from Liaoning Province Birth Defects Monitoring Network was used to describe the epidemiological features and secular trends of neural tube defects ( NTDs) prevalence during Jan. 1998 to Dec. 2003, including anenceph-aly,spina bifida and encephalocele and to investgate the high risk factors.Methods Data were collected with hospital - based cluster sampling method. During the period, all live or still births with 28 weeks or more of gestation were assessed within seven days after delivery. All were scanned in 24 - hours whole day, and inquiried NTDs cases should be filled in " Birth Defects Record".ResultsThere were 309 cases with NTDs identified from 309 246 births,with an o-verall prevalence rate of 9.99 per 10000 births. Significant falls in overall prevalence rates of anencephaly were observed. The prevalence rates of NTDs in female births were 1.45 times as in male births, and that in the rural were 2.26 times as in urban; The prevalence was higher in the groups with maternal age of less than 25 years and more than 30 years than in those 25 - 29 maternal ages; The occurrence of NTDs was higher in inland than in coastal - land( P <0.01).DiscussionNeural tube defects ,as a multifactorial disease, resulted from the interaction of heredity and environment to disturb the closure of the neural tube. Liaon-ing province lied in higher incidence region of northern China, some reason was that at the molecular level, the 677C-->T (alanine to valine) polymorphism in the gene encoding the folate metabolising enzyme methylenetetrahydrofolate re-ductase constitutes a genetic risk for neural tube defects increased more often frequency of the 677T allele in the north than in the south. An association between abnormal intake or metabolism of folate , iodine and neural tube defects has been proved in rural and inland region. In consistent six years survilliance, significant falls in the incidence of anencephaly, and the prevalence of spina bifi-da or encephalocele dropped respectively. Ultrasound screen and periconception-al folic acid supplementation decreased the neural tube defects. In this research, the prevalence was lower in the group with maternal age of 25 - 29 than in other maternal ages. The male NTDs had a correlation with season. Seasonal prevalence may be an aetiological factor for the male NTDs,which were significantly more common in August to September. The reason might be that fetus is sensible to high temperature. In this paper, the incidence of NTDs in areas of Liaoning province has been drawn directly.ConclusionsThe perinatal babies In Liaoning Province has a higher incidence rate of neural tube defects than the south of China and other developed contries. During 1998 - 2003, the incidence of total NTDs slightly dropped, annual prevalence rate of anencephaly presented a declining trend. Inhibatency in rural, inland re-gions , older or younger age of pregnant women, August or September in LMP and female fetus were high risk factors of acquiring NTDs. In child - bearing women, supplementation of multi - vitamine and microelement,prenatal diagnosis should be the effective preventive measures. |
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