The incidence of spina bifida in Sweden 1973-2003:: the effect of prenatal diagnosis

Background: Many studies have been conducted on the accuracy of prenatal ultrasound diagnosis of foetal CNS-malformations. These studies were mostly hospital-based or, sometimes, multicentre studies. We present here a population-based study of the prenatal diagnosis of spina bifida in Sweden over a period of 31 years. Methods: We compared the number of newborns with spina bifida and the elective terminations because of the prenatal diagnosis of spina bifida for different periods. Results: The rate of spina bifida among newborns diminished gradually from 0.55 per 1000 to 0.29 per 1000 during the study period. In M county the rate of spina bifida at birth decreased very rapidly and from 1993 onwards was about half of that in the rest of the country. Conclusion: There has been a decline in the rate of spina bifida at birth. This decline can be seen earlier in the southern part of the country, M county. The decline is probably, to a great extent, a consequence of prenatal ultrasound screening.