Malformations in newborn: results based on 30,940 infants and fetuses from the Mainz congenital birth defect monitoring system (1990-1998).

Prevalence rates of birth defects in the Federal Republic of Germany are informative to assess the general background risk of having a child with a birth defect. They provide basic figures to determine temporal and regional prevalence trends, to evaluate and initiate preventive measures and to initiate research projects. To avoid observer, definition and collection bias, active monitoring systems are required. Data collected in the active monitoring system of the Mainz Birth Defects Registry are presented. From 1990-1998, 30,940 live-births, stillbirths and abortions underwent standardized physical and sonographic examinations. Anamnestic data were collected from prenatal care records, maternity files and hospital records. Major malformations were diagnosed in 2144 (6.9%) and mild errors of morphogenesis in 11,104 (35.8%) of all infants. Risk factors associated with the occurrence of major malformations were identified by comparing anamnestic data from infants with and without major malformations. Using multivariate regression models, statistically significant associations were established for 9 risk factors. Causally related risk factors were parents or siblings with malformations, parental consanguinity, more than 3 minor errors of morphogenesis in the proband, maternal diabetes mellitus and ingestion of antiallergic drugs in the first trimester of pregnancy. Conjunctional risk factors were polyhydramnios, oligohydramnios and gestational age <32 weeks at birth. Using these risk factors, populations at risk for the occurrence of major malformation can be identified.