Time to Get Real About Preventing Neural Tube Defects in Europe
Babak and co-workers published an analysis of neural tube defect prevalence in Europe over a twenty year period from 1991 to 2011. The data was obtained from the extensive EUROCAT birth defect registry, which collects data from 43 registries in 23 countries in Europe. It seems that in the past 20 years, the rate of neural tube defects has largely remained unchanged at around 9 pregnancies affected out of every 10,000. In contrast, rates of neural tube defects has fallen over the same period in the US. What is the difference?
In the US, the mandatary folate fortification has been attributed to the reduction in the prevalence of neural tube defects. Starting from January 1998, certain cereal grain products have been fortified with folic acid in the US. In the period directly after fortification, there was a 30% decrease in the prevalence of neural tube defects, as reported by Mersereau and co-workers from the CDC, and Boulet found an additional decrease of 10% by 2004. In contrast, folic acid fortification in Europe is patchy at best. Only the UK, Kosovo and the Republic of Moldova have a mandatory folic acid fortification program in place. The rest of Europe relies on advising pregnant women to consume a high-folate diet and to take folic acid supplements when planning a pregnancy, and hopes food manufacturers will consider fortification of pertinent foods with folic acid for the same aim.
How effective is this approach compared to mandatory fortification? Another recent publication from Atta et al. looked at the effect of mandatory versus voluntary folic acid approaches to increasing folate intakes of the population and reducing rates of neural tube defects. They found a consistent reduction in neural tube defect prevalence when folic acid fortification was mandatory.
There are two main problems with encouraging women who plan to become pregnant to take folic acid supplements. The first is that many women have pregnancies that are unplanned. The worldwide rate of unplanned pregnancies is around 40%, and 45% of pregnancies in Europe are not planned. Neural tube closure in the embryo is completed by the 4th week of pregnancy, when women may not know that they are pregnant if it is unplanned. The second issue is that, for various reasons, even women planning a pregnancy may not take care that their folate intake is adequate. They may not know that folic acid can help prevent neural tube defects, or may only start taking the supplement after the pregnancy is confirmed. A recent study in a Chinese population from Ren found that only 85% of women took a supplement before pregnancy despite extensive promotion.
The best way to increase the folate status of women in the first weeks of pregnancies is to make the default situation one in which folic acid intakes are adequate. Promotion does not work. Hope does not work. Folic acid fortification appears to be the best way to reduce the rate of neural tube defects.
Khoshnood Babak, Loane Maria, Walle Hermien de, Arriola Larraitz, Addor Marie-Claude, Barisic Ingeborg et al. Long term trends in prevalence of neural tube defects in Europe: population based study BMJ 2015;351:h5949 doi: http://dx.doi.org/10.1136/bmj.h5949
Atta CA, Fiest KM, Frolkis AD, Jette N, Pringsheim T, St Germaine-Smith C, Rajapakse T, Kaplan GG, Metcalfe A. Global Birth Prevalence of Spina Bifida by Folic Acid Fortification Status: A Systematic Review and Meta-Analysis. Am J Public Health. 2015 Nov 12:e1-e11. [Epub ahead of print] http://www.ncbi.nlm.nih.gov/pubmed/26562127
Boulet SL, Yang Q, Mai C, Kirby RS, Collins JS, Robbins JM, Meyer R, Canfield MA, Mulinare J; National Birth Defects Prevention Network. Trends in the postfortification prevalence of spina bifida and anencephaly in the United States. Birth Defects Res A Clin Mol Teratol. 2008 Jul;82(7):527-32. doi: 10.1002/bdra.20468. http://www.ncbi.nlm.nih.gov/pubmed/18481813
P Mersereau, MN, K Kilker, Battelle Centers for Public Health Research and Evaluation; H Carter, MPH, E Fassett, MS, Assoc for Teachers of Preventive Medicine, Atlanta, Georgia. J Williams, MSN, A Flores, MPH, C Prue, PhD, L Williams, MPH, C Mai, MPH, J Mulinare, MD, Div of Birth Defects and Developmental Disabilities, National Center on Birth Defects and Developmental Disabilities, CDC.Spina Bifida and Anencephaly Before and After Folic Acid Mandate --- United States, 1995--1996 and 1999--2000. MMWR, May 7, 2004/53(17);362-365. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5317a3.htm
Ren AG. Prevention of neural tube defects with folic acid: The Chinese experience. World J Clin Pediatr. 2015 Aug 8;4(3):41-4. doi: 10.5409/wjcp.v4.i3.41. eCollection 2015. http://www.ncbi.nlm.nih.gov/pubmed/26261765