Objective: To describe the incidence and the expected clinical picture of neural tube defects (NTD) in years when periconceptional folic acid use increased.
Design: Descriptive.
Method: Data on the prevalence of NTD in the Netherlands in 1994-1998 and on the prognosis at the time of the report obtained from the Nederlands Signalerings Centrum Kindergeneeskunde (Netherlands Paediatric Spotting Centre), where all practising physicians in the Netherlands monthly report children in whom a rare disease has been diagnosed. Prevalence figures from before and after 1996 were compared, because periconceptional use of folic acid increased since late 1996.
Results: In 1994-1998, 414 children with NTD were reported, 164 boys, 191 girls and 59 unreported. The prevalence of NTD was 4.6 per 10,000 live births (95% confidence interval (CI): 3.7-5.6) compared with 3.8 per 10,000 live births (95% CI: 2.9-4.6) in the period 1997-1998. Of the 414 children, 257 had a meningomyelocele; the early mortality in this group amounted to 37%. Hydrocephalus was found in 84.8% of the infants, 40.9% of the infants were believed never be able to sit, stand, and walk.
Conclusion: The prevalence of NTD was lower in the period 1997-1998 than in the period 1994-1996 although the difference was not statistically significant.