FREQUENCY OF NEURAL-TUBE DEFECTS IN GERMA NY - PREVALENCE AND INCIDENCE

Background: There are no recent data on the occurrance of Neural Tube Defects in Germany. Such data, however, are mandatory for the evaluati on of the efficacy of the recommendations for periconceptional folic a cid supplementation. Methods: Two sources were used to assess the prev alence and incidence of Neural Tube Defects: data from a perinatal qua lity assessment programme, in which Neural Tube Defects in life births are reported (prevalence estimates) and the ''Mainzer Modell'' with s ystematic registration of malformations in spontaneous or induced abor tions after week 16, stillbirths and live-births (prevalence and incid ence). Results: The perinatal programme data show an about 50% decline in the prevalence of Neural Tube Defects since 1984. In 1992 the prev alence was 4.4/10 000 livebirths, which is likely to be an underestima te. Comparison with the ''Mainzer Modell'' data suggests, that only 45 to 75% of the cases are registered in the perinatal programme. The tr ue prevalence of Neural Tube Defects is likely to be in the range of 6 to 10/10000 livebirths. The Neural Tube Defects incidence estimates f rom the ''Mainzer Modell'' gave a figure of 11.1/10000 pregnancies wit h a 95% CI of 4.6-17.7. Conclusions: 1) The incidence and prevalence o f Neural Tube Defects in Germany in the lower range if compared to oth er European countries. 2) The decline of the Neural Tube Defects preva lence is likely to result from induced abortions after prenatal diagno sis of Neural Tube Defects. 3) The presently available prevalence figu res are insufficient to monitor the efficacy of periconceptional folic acid supplementation. 4) Valid incidence estimates with much narrower confidence intervals are mandatory; these require further monitor sta tions (''Mainzer Modell'' type) and acitive surveillance for Neural Tu be Defects in pregnancies.