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Multicenter Study
. 2005 Mar 12;330(7491):571.
doi: 10.1136/bmj.38336.664352.82. Epub 2005 Feb 18.

International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?

Lorenzo D Botto  1 , Alessandra Lisi, Elisabeth Robert-Gnansia, J David Erickson, Stein Emil Vollset, Pierpaolo Mastroiacovo, Beverley Botting, Guido Cocchi, Catherine de Vigan, Hermien de Walle, Maria Feijoo, Lorentz M Irgens, Bob McDonnell, Paul Merlob, Annukka Ritvanen, Gioacchino Scarano, Csaba Siffel, Julia Metneki, Claude Stoll, Richard Smithells, Janine Goujard
Affiliations
Multicenter Study

International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?

Lorenzo D Botto et al. BMJ. .

Abstract

Objectives: To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects.

Design: Retrospective cohort study of births monitored by birth defect registries.

Setting: 13 birth defects registries monitoring rates of neural tube defects from 1988 to 1998 in Norway, Finland, Northern Netherlands, England and Wales, Ireland, France (Paris, Strasbourg, and Central East), Hungary, Italy (Emilia Romagna and Campania), Portugal, and Israel. Cases of neural tube defects were ascertained among liveborn infants, stillbirths, and pregnancy terminations (where legal). Policies and recommendations were ascertained by interview and literature review.

Main outcome measures: Incidences and trends in rates of neural tube defects before and after 1992 (the year of the first recommendations) and before and after the year of local recommendations (when applicable).

Results: The issuing of recommendations on folic acid was followed by no detectable improvement in the trends of incidence of neural tube defects.

Conclusions: Recommendations alone did not seem to influence trends in neural tube defects up to six years after the confirmation of the effectiveness of folic acid in clinical trials. New cases of neural tube defects preventable by folic acid continue to accumulate. A reasonable strategy would be to quickly integrate food fortification with fuller implementation of recommendations on supplements.

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Figures

Fig 1
Fig 1
Rates of neural tube defects (anencephaly and spina bifida) per 10 000 births, 1988-98. Shaded top portion indicates terminated pregnancies. Arrow indicates time of recommendations in each country. IRR=average rate of change from one year to next
Fig 2
Fig 2
Estimated number of pregnancies with neural tube defects preventable by folic acid in study area, 1993-8. Estimates assume three scenarios of effectiveness (30%, 60%, 90%), which encompass a reasonable range from low dose fortification to highly effective supplementation
See this image and copyright information in PMC

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