What is the Story in Europe?
Neural Tube Defects (NTD) (anencephaly, spina bifida and encephalocoele) affect approximately one in a thousand pregnancies in Europe (equating to over 5000 pregnancies annually). Anencephaly is always lethal. Spina bifida and encephalocoele cause serious disability in survivors. The majority of NTD affected pregnancies are renatally diagnosed and terminated (approximately 70%) in most European countries, but this always represents a major tragedy for the parents.
In 1991 the Medical Research Council (MRC) Vitamin Study results confirmed that the majority of NTDs could be prevented if the mother took folic acid supplements prior to conception and in the first trimester of pregnancy1. Folic Acid is a synthetic form of folate which is a water soluble B vitamin most commonly found in green vegetables. Most European countries have policies in place advising periconceptional supplementation with 0.4 milligrams of folic acid taken daily prior to conception and for the first three months of pregnancy.
However, most women in Europe are still not taking supplements prior to conception,and the ability of folic acid to reduce the number of NTD has not been fully realised. The relative failure of the periconceptional folic acid supplementation policy has led many countries to introduce mandatory fortification of flour with folic acid (to see a global and country specific overview of fortification, access the Food Fortification Initiative website). Three of the first countries to introduce mandatory fortification were the USA and Canada in 1998 and Chile in 2000. Studies following fortification showed a decline in the NTD rates in those countries2-5.
While voluntary fortification of some foods is available in much of Europe, European countries have been reluctant to introduce mandatory fortification. Reluctance has centered on fears that there would be adverse effects. The fears have mainly concerned the possibility of an association between folic acid and colorectal cancer and the possibility of higher blood folate levels masking Vitamin B12 deficiency in the elderly. In the UK, the Scientific Advisory Committee on Nutrition, having considered the available evidence on adverse effects, met in June 2009 and supported a recommendation for mandatory fortification6.
What does EUROCAT monitor about NTDs and Why?
- Birth defects registries are vital to monitor the impact of strategies to raise the folic acid status of women periconceptionally in order to prevent NTDs.
- Total prevalence of NTDs includes live births, stillbirths and fetal deaths from 20 weeks gestation with a NTD, and TOPFA after prenatal diagnosis of a NTD. The total prevalence measure is used to track progress in primary prevention.
- The live birth prevalence measure includes only live births. The live birth measure is used to inform EU Member States regarding the need to provide high quality health and other services for children living with a NTD and their families.
What does EUROCAT data on NTDs tell us?
- Countries vary in total prevalence (see EUROCAT Website Prevalence Tables).
- EUROCAT’s Special Reports show, there has been no real progress in preventing NTDs in Europe since folic acid supplementation was shown to be an effective preventive measure. NTD prevalence has remained relatively stable.
- Only very recently do we see a decline in prevalence in some countries. This needs to be monitored further to see if the decline will be sustained and to ensure it is through primary prevention not correlated to an increase in terminations following prenatal diagnosis.
- The majority of NTD affected pregnancies in Europe are TOPFA, except for some countries.
- Low total prevalence rates of NTD may indicate
- Better folic acid acid/vitamin status through supplementation and/or voluntary food fortification and diet.
- A lesser genetic predisposition for NTD.
- Less exposure to other environmental risk factors .
- Incomplete data..
- Total prevalence of NTD (per 1000 births) is one of EUROCAT’s six Key Public Health Indicators. Because many countries have focused their primary preventive efforts on prevention of NTD by folic acid supplementation, this indicator allows the success of these preventive programs to be measured.
“The potential for preventing NTDs by periconceptional folic acid supplementation is still far from being fulfilled in Europe. In order to achieve a reduction in NTD prevalence, new efforts are needed in all countries to implement a combined strategy to increase folate status by dietary means, increase uptake of folic acid supplements periconceptionally, and to increase availability and identification of fortified foods.”
“Member States should ensure that their registries are adequately resourced and supported to produce high quality data.”
It would be possible in the future to look at rates of other congenital anomalies in the context of folic acid supplementation and / or fortification policies. The results of several studies suggest that folic acid might be protective against some cardiac defects and some oral clefts7, 8.
Further studies are necessary to determine if there is, in fact, a protective effect and if so, how strong, against specified congenital anomalies other than NTDs.
Relevant EUROCAT reports
De Wals, Tairou F, van Allen MI, Lowry SH, Sibbald B, Evans JA, van den Hof MC, Zimmer P, Crowley M, Fernandez B, Lee NS, Niyonsenga T (2007), "Reduction in Neural Tube Defects after Folic Acid Fortification in Canada", N Engl J Med, Vol 357, No 2, pp 135-142.
Botto LD, Lisi A, Bower C, Cranfield MA, Dattani N, de Vigan C, de Walle H, Halliday J, Irgens LM, Lowry RB, McDonnell R, Metneki J, Poetzsch S, Ritvanen A, Robert-Gnansia E, Siffel C, Stoll C, Mastrioacovo P (2006), "Trends of Selected Malformations in Relation to Folic Acid Recommendations and Fortification: An International Assessment", Birth Defects Res A Clin Mol Teratol, Vol 76, No 1, pp 693-705.
Williams LJ, Mai CT, Edmonds LD, Shaw GM, Kirby RS, Hobbs CA, Sever LE, Miller LA, Meaney FJ, Levitt M (2002), "Prevalence of Spina Bifida and Anencephaly During the Transition to Mandatory Folic Acid Fortification in the United States", Teratology, Vol 66, No 1, pp 33-39.
Lopez-Camelo JS, Orioli IM, de Graca Dutra M, Nazer-Herrera J, Rivera N, Ojeda ME, Canessa A, Wettig E, Fontannaz AM, Mellado C, Castilla EE (2005), "Reduction of Birth Prevalence Rates of Neural Tube Defects After Folic Acid Fortification in Chile", Am J Med Genet A, Vol 135, No 2, pp 120-125."
Badovinas RL, Werler MM, Williams PL, Kelsey KT, Hayes C (2007), "Folic Acid Containing Supplement Consumption During Pregnancy and Risk for Oral Clefts: A Meta-Analysis", Birth Defects Res Clin Mol Teratol, Vol 79, No 1, pp 8-15.