| BackgroundBirth defects(BDs),also known as congenital anomaly,refer to any anatomical or functional abnormalities that occurred at Birth.In recent years,BDs types with high incidence in China mainly include congenital heart disease,multiple fingers/toes,total cleft lip,and horseshoe varus.According to the data in 2015,the incidence of BDs in China was 19.87 and there were about 900,000 new cases of BDs every year.BDs not only brings huge economic burden to the society and family,but also leads to various adverse pregnancy outcomes and infant mortality,which has become an important public health problem and social problem in China.The influence factors of BDs are widely distributed and complex,including"explicit factors" which can be directly investigated or measured and "latent factors"which can not be directly observed.At present,there were many domestic and foreign studies about the analysis of BDs influence factors,most of which used chi-square test or Logistic regression analysis,and some of them used generalized model such as Poisson regression.The main purpose of these studies was to evaluate the individual effects of influence factors,while ignored the interaction between factors and local independence effects at the same time.Latent Class Analysis(LCA)is a statistical method through the research of the synergistic effect between multiple risk factors.The group is divided into different subgroups of mutually exclusive distribution patterns,and the difference of risk factors in subgroups become maximization.LCA can be used to realize the characteristic clustering of the BDs influence factors,evaluate the joint effect between maternal exposure factors,and explore the common distribution pattern of factors at individual level.At present,there were few reports on the research of the distribution pattern of BDs influence factors at home and abroad,and it has limitations such as the research factors were one-sided or the regional distribution differences of influence factors were not considered.The methods of space epidemiology have developed rapidly in the last decade.At present,many studies have found that the occurrence of BDs was spatially clustered,and the exposure distribution of non-genetic factors such as education level and lifestyle in the population may also have regional differences.The application of geographic information technology to explore the differences between the distribution patterns of BDs influence factors in high-incidence areas and non-high-incidence areas is helpful to formulate the prevention and control strategies of BDs with regional characteristics,and it's a great significance for improving the quality of the birth population.ObjectiveBased on the population of Pingyin county,this study used multiple research methods such as spatial clustering analysis,case-control studies,and latent class analysis,to explore the occurrence status of BDs and high concentrated areas in Pingyin county,and discussed the difference of distribution patterns of BDs influence factors in high-incidence areas and non-high-incidence areas,which can provides scientific basis for formulating individualized preventive and control measures in different areas.Methods1.Research on incidence and spatial distribution characteristics of birth defects in Pingyin county from 2015 to 20171.1 Data collection and general descriptionOn the basis of hospital monitoring,data of defective infants and perinatal infants in Pingyin county were collected from 2015 to 2017(2014.10.1-2017.9.30).Calculated the total incidence rate and the annual incidence rate.Compared the incidence between urban and rural areas.The sequence of major BDs types and human body system were calculated.Described the characteristics of birth defects and the demographic characteristics of mothers.1.2 Spatial aggregation analysisBDs data were connected with geographic distribution information to construct the case distribution map of birth defects through 343 spatial units.BDs incidence was standardized by age and smoothed by spatial experience bayes.The BDs incidence level map was drawn.T he global spatial autocorrelation and local spatial autocorrelation were analyzed to explore the high-incidence areas of BDs in Pingyin county.2.Case-control study on influence factors of birth defects in Pingyin countyA case-control study was designed to collect the basic characteristics of mothers and the exposure of influence factors of birth defects in case group and control group through questionnaire survey.Chi-square test was used to compare the differences between groups,and logistic regression analysis was used to screen the appropriate influencing factors for the discussion of subsequent distribution patterns..3.Research on the distribution pattern of influence factors of birth defectsThe LCA method was used to investigate the distribution patterns of the influence factors in high-incidence areas and non-high-incidence areas.Compared the differences in the distribution patterns of the influence factors of BDs in different areas.Results1.Incidence and spatial distribution of birth defects in Pingyin county from 2015 to 20171.1 General characteristics of birth defectsFrom 2015 to 2017,a total of 279 cases of birth defects and 10,884 perinatal infants were monitored in Pingyin county,with a total incidence of BDs of 25.63.The annual incidence rates were 21.17,23.37 and 30.28,showing an increasing trend year by year(trend ?2 =6.177,P=0.013),higher than the national and Shandong defect rates in the same period.The BDs rate was 29.16 for males and 21.10 for females,with no significant difference(?2=3.445,P=0.063).The incidence of BDs was 73.32 in urban areas,19.27 in rural areas,the incidence of BD in urban areas was significantly higher than that in rural areas(?2=120.867,P<0.001).The main types of birth defects in the top five order of morbidity were congenital heart disease(33.08/10000),accessory ear(2940/10000),polydactyly(1746/10000),total cleft lip(1654/10000)and congenital kidney malformation(1470/10000).The top five order of incidence of involved human system:facial/neck/face(55.07/10000),circulatory system(43.14/10000),musculoskeletal system(34.88/10000),urinary system(33.96/10000)and nervous system(2662/10000)The average gestational age of mothers was 30.78±5.63 years old,among which those with junior middle school education(39.07),per capita household income was between 2000 and 4000 yuan(41.58),multipara(98,21)and multiple pregnancies(78.14)accounted for a large proportion.The mean gestational age of the live cases was 275.48±10.97 days,and that of the stillborn cases was 180.89±40.85 days,among which single birth(97.13%),live birth(63.08%),ultrasonic diagnosis alone(50.54%)and postpartum diagnosis within 7 days(41.58%)accounted for a large proportion.1.2 Results of spatial clustering analysis of birth defectsA total of 279 cases of defective infants were distributed in 116 spatial units,and the case distribution showed a trend of gradual southward development.After age standardization and spatial bayesian smoothing,the defect rate of each spatial unit ranged from 0 to 187.57.The incidence of BDs was spatially autocorrelated throughout the county(Moran's I=0.113,P=0.005).There were 59 local spatial units with significant Moran's I statistics,among which 25 were positive-positive correlation areas,mainly distributed in and around the urban area and in the west of Xiaozhi town.There were 99 spatial units with significant getis-ord Gi*statistics,including 52 "hot spots",which were concentrated in and around the county,the west of Xiaozhi town,and the middle of Kongcun town.According to the actual incidence rate,the high-incidence area of BDs in Pingyin county mainly included 37 spatial units,including the urban area of Pingyin county and its surrounding areas,the northeast and the southeast,etc.while the non-high-incidence area mainly included 306 spatial units.The incidence of BDs in high-incidence areas was 37.70,while that in non-high-incidence areas was 18.61.The incidence of BDs in high-incidence areas was significantly higher than that in non-high-incidence areas(?2=36.954,P<0.001,RR=2.03,AR=19.09).2.Results of case-control study on influence factorsA total of 420 valid questionnaires were collected,including 216 in case group and 204 in control group.There were no significant differences between the case group and the control group in age,education level,family residence,occupation,annual family income and other aspects.Long-term working experience in a factory or hospital before pregnancy,exposure to risk factors during work,abnormal pregnancy history,medication during pregnancy,and application of assisted reproductive technology may be risk factors for BDs in Pingyin county(P<0.05).Living birth history,prenatal folic acid supplementation,physical exercise during pregnancy and good health knowledge and accomplishment may be protective factors for BDs in Pingyin county(P<0.05).3.Results of distribution patterns of influence factors of birth defectsBased on the case control study findings and literature review results,12 common BDs influence factors were selected for modeling.The influence factors in high-incidence areas can be grouped into three potential distribution patterns;"distribution of disease or medication during pregnancy"(45.8%),"distribution of fewer risk factors"(32.1%),and "distribution of poor working environment"(22.1%).The influence factors in the non-high-incidence areas can be grouped into three potential distribution patterns:"distribution of fewer risk factors"(42.2%),"distribution of disease or medication during pregnancy"(36.1%),and "distribution of multiple stimuli"(21.7%).Among them,the proportion of "distribution of disease or medication during pregnancy" in high-risk areas was significantly higher than that in non-high-risk areas(?2=4.182,P=0.041),and the proportion of "distribution of fewer risk factors" was significantly lower than that in non-high-risk areas(?2=4.566,P=0.033).Conclusion1.The occurrence of birth defects in Pingyin county showed a phenomenon of spatial clustering.Pingyin county has some obvious high-incidence areas which mainly included 37 space units in Pingyin county with its surroundings,northeast and southeast areas.The rate of BDs in high-incidence areas was 37.70,and that in non-high-incidence areas was 18.61.The risk of birth defects doubled in high risk areas.2.Regional differences exist in the distribution patterns of influence factors of birth defects.The influence factors in the areas with high incidence of birth defects mainly presented the pattern of "distribution of disease or medication during pregnancy",while the influence factors in non-high-incidence areas mainly presented the pattern of "distribution of fewer risk factors".3.The incidence of BDs in Pingyin county was at a relatively high level,among which the incidence of accessory ear,total cleft lip and congenital renal malformation was significantly higher than the national average level during the same period.Suggestions:Pingyin county should take targeted prevention and control measures for different areas.It is necessary to strengthen the monitoring of the incidence of maternal diseases or drug use during pregnancy and related latent factors in high-incidence areas,and screen for high-risk groups.The screening of accessory ear,total cleft lip and congenital renal malformation should be strengthened to achieve early detection and early intervention. |
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