Primary prevention of neural tube defects in Brazil: insights into anencephaly.

Abstract

Anencephaly is a lethal malformation characterized by the absence of the skull and both cerebral hemispheres caused by deficiency of closure of the neural tube at rostral level between 23 and 25 days of gestation (Bronberg et al. 2011). The occurrence of anencephaly and other neural tube defects (NTDs) such as meningocele and spina bifida are between 50 and 70 % preventable by periconceptional folic acid (FA) administration to reduce their prevalence across populations (Blencowe et al. 2010). The percentage decrease is dependent upon the background prevalence. The percentage of NTDs that are preventable by periconceptional folic acid intake is dependent on the prevalence of folate-sensitive NTDs in the population (Robbins et al. 2006; Bronberg et al. 2011). To prevent anemia due to iron deficiency and the occurrence of NTD, the Brazilian Ministry of Health approved the resolution RDC No. 344 on December 13, 2002, whereby the flour fortification of wheat and maize was regulated. This resolution determined that as of June 2004, wheat and corn flours be supplemented with at least 4.2 mg iron and 150 mcg of FA/100 g flour (ANVISA 2002). As in many South American countries, there are only two exceptions to penalized abortion in Brazil: in case of rape or to save the woman’s life. The Brazilian Criminal Code does not include fetal malformations as a cause of penalized abortion. This limitation was partially overcome in 2004, when the Brazilian Supreme Court of Justice authorized abortion in cases of anencephalic fetuses (Diniz 2007). Termination of pregnancy (TOP) with an anencephalic baby was made legal in 2012, without need of a special judicial authorization (Carvalho 2011). Until 2012, TOP had been legal in Brazil in cases of anencephaly only after special authorization from a judge. A survey performed with Brazilian obstetricians showed that 37 % of women with a pregnancy of anencephalic fetus had successfully obtained authorization for legal abortion (Diniz et al. 2009). About ten South American countries, in most of which abortion for congenital malformations is not authorized by law, primary prevention of anencephaly and other NTDs is managed through mandatory fortification of flour with FA (PAHO 2003). In some of these countries, fortification has proven to be an effective strategy for the primary prevention of anencephaly and NTDs. In particular, Argentina (Bronberg et al. 2011) and Chile (Cortes et al. 2012) have reduced the number of deaths by anencephaly by about 50 % in the post-fortification period compared to the pre-fortification stage. There are dissimilar records in Brazil in terms of fortification results according to NTDs, the type of data used (infant deaths or born alive), and level of spatial and temporal coverage these results are based on (Orioli et al. 2011; Pacheco et al. 2009; Fujimori et al. 2013; Schuler-Faccini et al. 2014). For its lethality, since 99 % of those born with anencephaly die within the first month of life and because the phenotype is well identified, even by non-specialists, anencephaly is a malformation whose epidemiological behavior can be analyzed with some confidence and provide an accurate and precise picture of the effect of flour fortification with FA and other preventive measures. Given the socioeconomic, geographical, ecological, and cultural diversity of Brazil, it is estimated that spatial and temporal variations of infant deaths from this NTD may be present. In this paper, the temporal variation and spatial distribution at different levels of the state organization in Brazil, infant and fetal deaths by anencephaly were analyzed in relation to the different phases that occurred in the process of fortification with FA.