Neural tube defects in Latin America and the impact of fortification: a literature review.

OBJECTIVE Data on the prevalence of birth defects and neural tube defects (NTD) in Latin America are limited. The present review summarizes NTD prevalence and time trends in Latin American countries and compares pre- and post-fortification periods to assess the impact of folic acid fortification in these countries. DESIGN We carried out a literature review of studies and institutional reports published between 1990 and 2010 that contained information on NTD prevalence in Latin America. RESULTS NTD prevalence in Latin American countries varied from 0·2 to 9·6 per 1000 live births and was influenced by methods of ascertainment. Time trends from Bogota, Costa Rica, Dominican Republic, Guatemala City, Mexico and Puerto Rico showed average annual declines of 2·5 % to 21·8 %. Pre- and post-fortification comparisons were available for Argentina, Brazil, Chile, Costa Rica, Puerto Rico and Mexico. The aggregate percentage decline in NTD prevalence ranged from 33 % to 59 %. CONCLUSIONS The present publication is the first to review data on time trends and the impact of folic acid fortification on NTD prevalence in Latin America. Reported NTD prevalence varied markedly by geographic region and in some areas of Latin America was among the lowest in the world, while in other areas it was among the highest. For countries with available information, time trends showed significant declines in NTD prevalence and these declines were greater in countries where folic acid fortification of staples reached the majority of the population at risk, such as Chile and Costa Rica.