Neural tube defects in Europe remain too high for the past 20 years, despite a long-standing medical recommendation that would prevent them, according to a paper in The BMJ today. 

Each year, around 5,000 pregnancies in Europe are affected by neural tube defects like spina bifida and anencephaly (problems with brain and skull formation), with serious consequences for newborns and their families. Taking folic acid supplements before and during early pregnancy can greatly reduce the risk, but evidence suggests that only a small minority of women do so.

Scholars analyzed data for more than 11,000 cases of non-chromosomal neural tube defects from 28 EUROCAT (European Surveillance of Congenital Anomalies) registries covering approximately 12.5 million births in 19 countries between 1991 and 2011. They attempted to account for differences across registries and to calculate non-linear time trends and found that the overall (pooled) total prevalence of neural tube defects in 2011 was fairly similar to that in 1991 (9 per 10,000 births). This was also true for the two main types of anomaly, anencephaly and spina bifida.

Estimates from models that took into account differences across registries showed an annual increase of 4% in 1995-99 and a decrease of 3% per year in 1999-2003, with stable rates thereafter. The trend patterns for spina bifida and anencephaly were similar, but neither anomaly decreased substantially over time.

This is an observational study so no definitive conclusions can be drawn about cause and effect. Registration problems or other data factors may have influenced the findings. Regardless, they suggest that recommendations and voluntary fortification are not getting the job done and say mandatory fortification of food staples with folic acid "should be considered as an important and more effective means for prevention of neural tube defects, while weighing the evidence for its proven benefits and possible risks."

Voluntary guidance for women isn't working and Europe should seriously consider mandatory fortification, argue researchers at the US National Institutes of Health, in an accompanying editorial. They point out that fortification has been shown to work in many countries, including the United States, and no important adverse effects have been identified to date.