4.4 Interpretation
There has been an increase in the number of cases of spinal dysraphism in recent years in Brazil, with an annual percentage change of 3.52%. In addition, during the period from 2005 to 2009, there was a reduction in the incidence of the disease. In 2005, the National Iron Supplementation Program (PNSF) was implemented, which consists of prophylactic iron and folic acid supplementation for pregnant women [15].
The fortification of foods with folic acid is an unquestionable intervention in primary prevention, with a positive impact on the prevention of neural tube defects already demonstrated in several countries [16]. Thus, we believe that after 2009, the strategy for implementing this health program may have been modified, which influenced the progressive increase in the number of cases.
The prevalence of spinal dysraphism remains high in federation units: Rondônia, Rio Grande do Norte, Pernambuco, Sergipe, Mato Grosso, São Paulo, and Rio Grande do Sul. However, the South (São Paulo) and Southeast (Rio Grande do Sul) regions had a higher incidence of cases. Despite policies promoting prenatal folic acid supplementation and fortification of the food supply, health promotion strategies that encourage women of reproductive age to take folic acid supplements have failed, considering that the proportion of women taking their supplements has decreased over the years in other countries, such as England [17].
In addition, the heritability (the genetic component of risk) was estimated to be 60–70% based on the relative proportions of individuals affected among siblings of index cases [18]. The genetic causes as part of the disease process should be considered, which may imply a higher frequency of spinal dysraphism in these regions.
This study shows that the risk was increased in mothers born after 1980, aged over 30 years, and with a high education level, showing the demographic change that the country has presented over the past few years, in which women increasingly assume the posture of having children later and actively participating in the labor market. Another possible explanation for this correlation is that the increase in the level of education of mothers allows them to become pregnant later than usual; for this reason, they are more likely to have neonates with the disease in question, since there is a positive correlation between the age of the mother and the disease [19].
The increased risk of live births with spinal dysraphism belonging to the White and Black race can be explained by the difference in dietary habits and practices of supplement intake between racial groups [20]. In addition, the difference in the level of education [21] and later pregnancy in white individuals may contribute to explaining this relationship. In Brazil, the income distribution is lower for black individuals, [21] which may imply worse eating habits and greater difficulties in accessing health care, making it difficult to monitor during prenatal care.
Regarding clinical factors, the results showed that one pregnancy was a protective factor for the occurrence of spinal dysraphism, but a double pregnancy was highly associated with the disease, as well as the body weight under 3,000 g of the newborn. This relationship probably occurs due to the deficiency of folic acid offered to neonates, [22] since the nutritional need is doubled in twin pregnancies. The use of multivitamins and folate during double pregnancy after a recognized twin pregnancy has been observed [23]. However, inadequate prenatal care can lead to inadequate nutritional intake or supplementation.
Finding ways to prevent more cases of spinal dysraphism is a priority for future research and public health implementation, and this study shows that absent prenatal care resulted in a higher incidence of spinal dysraphism. Thus, it affirms the concept that without adequate prenatal care, pregnant women do not have, by extension, adequate prevention and care for diseases, including spinal dysraphism. In this sense, the absence of prenatal care makes it difficult to carry out PNSF, [14] which may result in an increase in cases.