Decreased incidence of myelomeningocele at birth: effect of folic acid recommendations or prenatal diagnostics?

Purpose: In Denmark prevention to reduce Spina bifida birth rate has focused in two areas: Folic acid supplementation (1997) and changes in national ultrasonography screening programme (2004). Myelomeningocele (MMC) is the most severe malformation among Spina Bifida. Taken into consideration the potential negative effect of high dose folic acid consumption, we found a need to look into the effectiveness of these two strategies in our complete MMC population.
Methods: All Spina Bifida patients born in the western part of Denmark are differentiated into proper subgroups based on MR-Imaging, giving us a unique chance to study a true MMC population. The total group of MMC children since 1983 is 121. One hundred and eight (89%) parents answered a questionnaire.
Results: Following the changes in prenatal ultrasonography screening programme in 2004, a significant decline of 60% live birth MMC pr. year was noted, incidence rate ratio (IRR) = 40% [22% – 73%], p = 0.3%. We found no change in MMC birth rate after introduction of folic acid supplementation, IRR = 121% [81% – 181%], p = 36%.
Conclusion: In conclusion, our findings demonstrate no effect of introducing national folic acid recommendations when the compliance remain low but we find an high early MMC detection rate and reduced MMC birth rate when using a high quality ultrasonography screening program.