Epidemiological Study Of Birth Defects Based On Small Area Study Method

BackgroundBirth defects(BDs)can lead to miscarriage,stillbirths,neonatal deaths,and premature infant deaths in pregnant women.BDs are one of the most important public health problems in the world.In some countries,BDs rank first in infant deaths.The monitoring data shows that the incidences of BDs in China is on the rise.The BDs incidence was 198.67/10,000 in year 2015,namely there were 2 BDs cases per 100 newborns.Studying the pathogenic factors and pathogenesis of birth defects and proposing effective interventions are of great significance for the development of prenatal and postnatal care and the quality of the birth population.According to results of BDs research,the causes of BDs include both genetic and environmental factors.The influence of genetic factors to BDs may be similar in different regions,but environmental risk factors account for different ratios of BDs in different regions.The incidence of BDs varied from place to place and there were spatial aggregation,suggesting that environmental factors are the important role of BDs in the pathogenesis.The size of the spatial scale affects the spatial distribution of the disease.In fact,even in a small spatial area(eg,a county),geographically adjacent villages are similar in disease incidence level,suggesting that spacial aggregation may existed in a small spatial scale(eg,village level).At present,the spatial analysis of BDs is mainly concentrated on the medium-scale(districts and counties as spatial units).BDs based on small-area research methods is less researched.According to statistics,Pingyin County is a region with a high incidence of BDs in Shandong Province.But the pathogenic factors are still not clear.Therefore,to explore the spatial distribution characteristics of BDts in smaller spatial units is of great significance for identifying the environmental risk factors of birth defects.ObjectiveDescribe the distribution characteristics of BDs in Pingyin County from year 2004 to 2016 in detail.Build a spatial database of BDs of Pingyin County.On a relative smaller scale,the administrative village was set as the basic unit,analyzes the spatial clustering of BDs and explore the high incidence areas of BDs in Pingyin County.A case-control study was conducted to analyze the factors affecting BDs in small area and to explore the distributional differences of birth defects among the high and non-high incidence areas of BDs.The research results provide scientific basis for formulating the prevention and control countermeasures of BDs in small area.Methods1.Epidemiological characteristics descriptionThe hospital-based monitoring program was used to monitor perinatal births in Pingyin county from year 2004 to 2016.The incidence of birth defects over the years and the trend was analyzed.The differences of incidence rates between genders,urban area and rural area were compared.The rank of major birth defects and their changes over the years were calculated.The BDs incidences in different organs and systems calculate respectively.2.Spatial epidemiological analysisSpatial epidemiology database of BDs in Pingyin County was constructed.The spatial distribution characteristics of BDs in Pingyin County was analyzed.The BDs distribution was mapped at village level.Standardized incidences and spacial Bayesian smoothed incidences were calculated.The incidence level maps were drew.The spatial auto-correlation and spatial scan statistics were calculated,they were used to explore the high incidence areas and non-high incidence areas of BDs in Pingyin County.3.Influencing factors analysisA case-control study was designed.According to the principles of the same born year,similar mother’s age and the proximity of family address,all the BDs cases in nearly three years from the investigation date were matched with a control.All the mothers of BDs cases and their matched group received a questionnaire,which including:personal basic information,gestational history,illness history;medication history,dietary supplements history,dietary habits,living environment,lifestyle,menstrual history;negative life events,health literacy and nutrition knowledge.Chi-square test,t test Wilcoxon rank sum test and Logistic regression were used for single factor analysis.Chi-square test was used to compare the differences in the distribution of factors affecting BDs in high and non-high incidence areas.A multivariate Logistic regression model was used for multivariate analysis the influencing factors of BDs.The level a=0.05.Results1.Distribution characteristics of BDs in Pingyin CountyFrom year 2004 to 2016,there were 43976 newborns and 592 BDs cases inPingyin County,the incidence of BDs was 13.46‰.The BDs incidences showed an upward trend(χ2,= 48.32,P<0.001).The BDs incidences of male and female were 14.39 ‰ and 12.01 ‰ respectively,the males’ was higher(P=0.033).The BDs incidences of urban area and rural area were 22.57 ‰ and 11.88 ‰ respectively,the urban area’s was higher(P<0.001).The first five highest incidence of BDs categories were:congenital heart disease(18.87/10,000),multiple finger/toe(12.73/10,000),accessory auricles(10.92/10,000),total cleft lip(10.46/10,000)and congenital hydrocephalus(9.55/10,000).The organs most involved in BDs were brain,heart,finger/toe,ear,and kidney.The systems most involved in Bs was:facial features/face/neck,musculoskeletal system,nervous system,circulatory system and urinary system.2.Spatial Distribution and Aggregation of BDs in Pingyin CountyDuring the study period,the villages with higher BDs in Pingyin County were mainly concentrated in the county area and its surrounding areas and the central area.The BDs incidences in Pingyin County was global auto-correlation at village level(Global Moran’s I= 0.5975,P<0.001).Local Moran’s I statistics showed that 121 spatial units were auto-correlation,49 of which were positive-positive auto-correlation,mainly in urban area and its surrounding areas and central area.The Getis G statistics showed that a total of 135 spatial units were auto-correlation,54 of which were positive-positive auto-correlation,mainly concentrated in urban area and its surrounding areas and central area.Of the 343 spatial units in the study,146 were in high-incidence area and 197 were in non-high-incidence area.During the study period,there were 24,784 perinatal children and 414 birth defects in high-incidence area,the BDs incidence was 16.70/1,000.There were 19,192 perinatal children and 178 birth defects in non-high-incidence area,the BDs incidence was 9.27/1,000.The BDs incidence was significantly higher in the high-incidence area than in the low-incidence area(χ2=43.25,P<0.001).The RR was 1.80,and the AR%was 44.49%.3.BDs influencing factors analysis resultsThere were 180 pairs of subjects,among them,122 pairs were from high BDs incidence area and 58 pairs were from low BDs incidence areas.The average age of the subjects was 30.38 ± 5.09 years old.The univariate analysis showed that pregnancy times(OR:1.72,95%CI:1.07-2.75),induced labor history(OR:12.53,95%CI:5.23-30.03),unhealthy fetal pregnancy history(OR:4.59,95%CI:1.51-13.92),greasy diet(OR:1.83,95%CI:1.17-2.85),contacting with high temperature(OR:4.68,95%CI:1.00-21.99),passive smoking during pregnancy(OR:2.02,95%CI:1.03-3.96)were risk factors of BDs.Folic acid supplementation before pregnancy(t=1.97,P=0.050),folic acid supplementation during pregnancy(t=2.95,P=0.041),vitamin supplementation during pregnancy(t=2.01,P=0.046),taking exercise during pregnancy(OR:0.31,95%CI:0.14-0.67)were protective factors of BDs.Multivariate analysis showed unhealthy fetal pregnancy history(OR:15.53,95%CI:5.79-41.65),pre-pregnancy/pregnancy makeup(OR:2.30,95%CI:1.0.6-4.97),use of microwave for cooking(OR:2.06,95%CI:1.01-4.43),dietary greasy(OR:1.72,95%CI:1.05-2.94)were risk factors of BDs(P<0.05).Higher health literacy score(OR:0.19,95%CI:0.06-0.63),pre-pregnancy folic acid supplementation(OR:0.33,95%CI:0.12-0.99),and light physical labor at work(OR:0.52,95%CI:0.3-0.91)were protective factors of BDts(P<0.05).The analysis of influencing factors in high-incidence areas showed that pregnant women’s education(χ2=45.98,P<0.001),pregnant women’s occupation((χ2=61.82,P<0.001),folic acid supplementation before pregnancy for more than one month(OR:0.57,95%CI:0.35-0.92),pre-pregnancy/pregnancy check-in for newly renovated rooms(OR:3.55,95%CI:1.04-12.14),use of exhaust facilities for cooking(OR:5.1,95%CI:3.1-8.39),use of mobile phones more than 1h per day(OR 1.84:,95%CI:1.16-2.9),use of computer more than 1h per day(OR:2.88,95%CI:1.65-5.03),high health literacy score(OR:2.86,95%CI:1.8-4.56)were inconsistent distribution in high and non-high incidence areas of BDs.The results of case-control study and risk distribution analysis of influencing factors in high-incidence areas showed that the distribution of folic acid and healthy literacy before pregnancy was different between cases and controls,and between high and non-high areas.Conclusions1.The incidence of BDs in 2004-2016 in Pingyin County was 13.46 ‰,which showed an increasing trend.Pingyin County was a high incidence area of birth defects in Shandong Province.2.The urban area and its surrounding areas in northern region,and the relatively high elevation in the middle area were high-incidence areas of BDts in Pingyin County.The incidence of BDs in high-incidence areas was 16.70‰,and in non-high incidence areas was 9.27‰.The RR was 1.80,and the AR%was 44.49%.BDs incidences showed significant spatial aggregation at the village level.3.The main differences of BDs in high and non-high incidence areas were pregnant women’s education level,pregnant women’s occupation,pre-pregnancy supplementation of folic acid,pre-pregnancy/pregnancy check-in newly renovated houses,use of exhaust facilities for cooking,use of mobile phones,use of computers,and literacy score.4.Women with higher health literacy in high-incidence areas do not have the correct folic acid supplement.Recommendations:In the high-incidence area of BDs,women of child-bearing age should be given a health education on taking folic acid.Folic acid administration policies should be formulated to guide pregnant women to supplement folic acid before pregnancy so as to reduce the incidence of BDs in high-incidence areas.