| A birth defect is a problem that happens while the baby is developing in the mother's body, including abnormality of structure, function, metabolism or development. Most sever defects are found and diagnosed immediately after birth, such as neural tube defects and cleft lip, but others (such as congenital heart defects or Down syndromes) are found using special tests (such as x-rays, CAT scans, or laboratory test). Birth defects can vary from mild to severe, from single to multiple.It is reported by March of Dimes Foundation that there were 79 million babies (6 percent of total worldwide) with birth defects born in 2001, including congenital heart defects (1,040,835), neural tube defects (323,904), down syndromes (217,293), hemoglobin disorders (307,897), and G6PD deficiency (177,032) and so on. About 3.3 million children under the age of five die from birth defects.The prevalence of birth defects distribute differentially throughout the world. The north and Midwest of African, Mediterranean region, Arabia, and Indian are regions of high rates of birth defects. South America, Mexico, the south and east of African, the east of Europe, and the southeast of Asian are regions of moderate rates of birth defects. North America, the north of Asian, China, Australia, and the north and Midwest of Europe are low regions. Several factors contribute to the disparities in the global distribution of birth defects. These factors include malaria, consanguineous marriage, migration, national level of health care, poverty and so on. Although China belongs to low regions of rates of birth defects, it has a great number of babies with birth defects because of the majority birth number base of Chinese population.Birth Defects are a major cause of prenatal and infant mortality. In China, birth defectsaccount for 22.45 percent of prenatal mortality during 1990-2001. In Italy, the rate is 23 percent during 1980-2000, and in America the rate is 20 percent approximately. However, most numbers of birth defects are not lethally, but a leading cause of disability and growth retardation. A field survey in 1987 showed that there were 1.2 percent of child with the low intellectuality in China, half of them attributed to birth defects. Meanwhile, birth defects bring huge economic loss and psychic pressure to sufferers, their family and their country.Either genetic and environmental factors, or a combination of these factors, can cause birth defects. However, the causes of about 50 percent of birth defects are unknown. In many cases, a single gene change can cause birth defects, for example achondroplasia, cystic fibrosis and hemophilia. Abnormalities in the number or structure of chromosomes can cause many birth defects, for example Down syndrome. Environmental substances, which include alcohol, certain drugs/medications, infections, and certain chemicals, can cause birth defects, for example fetal alcohol syndrome and limb malformation. In addition, most of birth defects including cleft lip, congenital heart defects and so on appear to be caused by a combination of one or more genes and environmental exposures. It was reported that TORCH infections, certain drugs, maternal diabetes, high maternal age, malnutrition, smoking, alcohol are teratogen of non-gene factors definitely. However, the types and effect of specific factors are variable, because the susceptibility of population, geographic element and economic level of some region are different.The population-based birth defects surveillance data during 2000-2006 in Zhoushan Island was analyzed, the prevalence and epidemic trend of birth defects of prenatal newborns were described. The relationship between influence factors and birth defects would be explored. The findings can supplement the database of Zhejiang province, and it may provide clues for establishing preventive strategies and will be consulted for other uniform geographic regions.Methods and MaterialA population-based surveillance system on birth defects was used to obtain the prevalence of 40 kinds of birth defects from >20 weeks of gestation to 42 days of life in Zhoushan Island from Jan 2000 to Dec 2006. In addition, the birth defects detected in the outpatient would be covered.The definitive classification and the information of birth defects would be done by gynecologist. The information of birth defects consisted of birthday, gestational age, the types of birth defects, prenatal care number and so on. Visceral organs birth defects including cardial system and renal system should be identified by ultrasound scan.The dynamic changes of incidence rate, the distributive characters of total and 40 types of birth defects in Zhoushan Island would be described.In the nested case-control study, the pregnancy in Dinghai district of Zhoushan was registered using "Prenatal Health Care Booklets", which would be centralized to Women and Children's Hospital of Zhoushan and imported to computer. During Jan 2000 to Dec 2006, 21,520 numbers of pregnant women information was collected, and 18486 numbers of data are available.49 cases of CHD were acquired from the birth defects surveillance system of Dinghai district of Zhoushan, 45 cases with adequate data was selected to be analyzed, 135 frequency matched controls were selected. The information of cases and controls were gained from the database of "Prenatal Health Care Booklets". Distributional characteristics of qualitative variables between cases and controls were analyzed by x~2 test, dose-reaction relation was judged by chi-square test. By means of simple and multivariable logistic regression, odds ratio of 19 variables were analyzed, including demography, the information of first trimester pregnancy and experimental test result.All statistical analysis was processed in software of SPSS 13.0 for windows and Microsoft Excel 2003.Results1. The prevalence of total birth defects in ZhoushanFrom 2000 to 2006, there were 41,396 fetus were reported by birth defect surveillance system, including live birth, stillbirths and numbers of termination of pregnancy for birth defects, 498 cases were suffered form birth defects, the prevalence of birth defects was 120.30 per 10,000. The rate were increasing year by year significantly (P<0.01). Single birth defects accounted for 93.98 percent of total birth. Preterm, full term, post term birth infant accounted for 30.12%, 68.67% and 1.2% respectively of all birth defects.2. The composition of birth defectsThe common types of birth defects in Zhoushan Island were congenital heart defects, external ear malformation, cleft lip with or without cleft palate, hydrocephaly, polydactyl and neural tube defects.The female patient of congenital heart defects was more than male, while the male patient of external ear malformation, cleft lip with or without cleft palate, hydrocephaly and polydactyl more than female. However, the top five types of for male were same to female.During 2000-2002, top three types of birth defects were external ear malformation, polydactyl and cleft lip with or without cleft palate. Since 2003, congenital heart defects became the number one and continued to 2006. The prevalence of Others types of birth defects including external ear malformation, polydactyl, hydrocephaly, cleft lip with or without cleft palate and neural tube defects were fluctuate from second to fifth place.The prevalence of congenital heart defects and hydrocephaly presented a rising trend in during 2000-2006, while the clubfoot presented a decreasing trend. Other types of birth defects prevalence had no significantly different. The congenital heart defects consisted of ventricular septal defect (33.81%), Atriotricular septal defect (28.06%) and patent ductus arterious (12.95%) chiefly.The result of simple logistic regression showed, that the spontaneous abortion was associated with CHD (OR=8.96, 95%CI: 1.15-69.75). The odds ratio were 8.96(95%CI: 1.15-68.75), 6.85 (95%CI: 0.85-55.31) , respectively, for infant born to father 26-30 and over 30 years, when compared with the infants born to farther younger than 25. Maternal exposure to prophylactic, fever, urinary glucose, and maternal syphilis infection were associated with CHD, their odd ratio were 6.03 (95%CI: 1.68-21.71), 6.49 (95%CI: 1.15-36.71), 6.49 (95%CI: 1.15-36.71), 3.37 (95%CI: 1.11-10.21).By multivariate logistic regressions, we found that 3 variables were significantly associated with the risk of CHD, including maternal syphilis infection during the first trimester of pregnancy, maternal exposure to prophylactic before pregnancy, and paternal age.The odds ratio of maternal syphilis infection and maternal exposure to prophylactic before pregnancy were 5.48 (95%CI: 1.48-20.30), 4.36 (95%CI: 1.26-15.05) respectively. Paternalage(26-30) was associate with CHD(OR=9.61, 95%CI: 1.17-78.94) compared with man aged less than 25.ConclusionsThe population-based birth defects surveillance system can obtain the actural prevalence of birth defects in Zhoushan effectively. The rates were increasing year by year significantly. The five common types of birth defects in Zhoushan Island were congenital heart defects, external ear malformation, cleft lip with or without cleft palate, hydrocephaly and polydactyl. The prevalence of congenital heart defects and hydrocephaly presented a rising trend in during 2000-2006, while the clubfoot presented a decreasing trend. Other types of birth defects prevalence had no significantly different.Maternal syphilis infection during the first trimester of pregnancy, maternal exposure to prophylactic before pregnancy, and paternal age were associated with CHD...
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