Seasonality of spina bifida in Northern Germany

To verify a seasonal variation in the incidence of spina bifida and thus to identify possible environmental triggers leading to its developement. An interdisciplinary approach has been taken to develop a better understanding of spina bifida through collaborative efforts from investigators specializing in genetics, fetal pathology, paediatrics, neuro-surgery and prenatal ultrasonographic diagnosis. All pregnancies with fetal spina bifida were retrospectively analyzed from May 1 1993 through May 1 2010 at Luebeck University Fetal Health Center. Results were used to construct a model to predict the occurrence of fetal spina bifida based on seasonal variation and environmental influence reflected by climatic changes and environmental pollution. Furthermore, data were categorized in respect to the date of conception and subdivided into date of conception during summer (April-September) and winter months (October-March). Neither a seasonal distribution of conception for fetuses with spina bifida in the defined time frame could be verified nor a relevant influence of the analyzed environmental factors on the prevalence of spina bifida could be proved. The incidence of spina bifida has remained relatively stable within the last 17 years at 2.5 per 1,000 screened pregnancies. Since we were unable to demonstrate a relationship between seasonal variation and certain environmental factors on the incidence of fetal spina bifida, other factors should be investigated for a possible association with the onset of fetal spina bifida.