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

Abstract

Purpose: In Denmark, prevention to reduce the spina bifida birth rate has focused on two areas: folic acid supplementation (1997) and changes in the national ultrasonography screening programme (2004). Myelomeningocele (MMC) is the most severe malformation among the spina bifidas. Taking 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 number of the group of MMC children since 1983 is 121. One hundred and eight (89%) parents answered a questionnaire.

Results: Following the changes in the prenatal ultrasonography screening programme in 2004, a significant decline of 60% live birth MMC per 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: Our findings demonstrate no effect of folic acid recommendation due to lack of compliance among women of reproductive age in Denmark. However, we found an improved early detection rate of prenatal MMC by high-quality ultrasonography. Subsequent early termination of pregnancy has led to a significant reduction of birth rate of babies with MMC.