[Correlations of Birth Defects With Birth Weight and Gestational Age].

Objective To analyze the incidence rate of birth defects in infants born at different gestational ages and birth weights,so as to provide a basis for improving the surveillance system and reducing the incidence of birth defects. Methods Data of all perinatal infants born at and after 28 weeks of gestation and within 7 days after delivery in all the hospitals with the obstetrical department from October 1,2003 to September 30,2015 were collected. Results From 2003 to 2015,1 236 937 perinatal infants were monitored,including 10 619 with birth defects (incidence rate of 8.59‰).Among the infants with birth defects identified by the hospital surveillance system of birth defects in Xi'an during the study period,3 306,3 473,and 224 infants showed the birth weights less than 2 500 g,the gestational age within the range of [28,37] weeks,and the gestation age≥42 weeks,respectively.The low birth weight infants showed higher incidence rate of birth defects than the normal birth weight infants (χ²=37 097.79,P<0.001).The premature infants (gestational age<37 weeks) and postterm infants (gestational age≥42 weeks) showed higher incidence rates of birth defects than infants born at normal gestational age (χ²=24 998.24,P<0.001;χ²=196.40,P<0.001).The top five birth defects of low birth weight infants were congenital hydrocephalus,spina bifida,congenital heart disease,anencephaly,and cleft lip and cleft palate.The outcomes of birth defects in normal weight infants and low weight infants were mainly live births (68.60%) and stillbirths (54.72%),respectively,which showed a significant difference (χ²=647.59,P<0.001).The main outcomes of birth defects in the infants born at normal gestation age,postterm infants,and premature infants were mainly live births (77.38%),live births (83.93%),and stillbirths (57.79%),respectively,which showed significant differences (premature infants vs.infants born at normal gestation age: χ²=2 025.08,P<0.001;premature infants vs. postterm infants:χ²=245.39,P<0.001;infants born at normal gestation age vs.postterm infants:χ²=16.28,P=0.001). Conclusions Premature infants,low birth weight infants,and postterm infants showed significantly higher incidence rate of birth defects than the infants born at normal gestation age.The outcomes of birth defects had significant differences between low birth weight infants and normal birth weight infants,between premature infants and infants born at normal gestation age,between premature infants and postterm infants,and between infants born at normal gestation age and postterm infants.