Research has indicated that the appropriate intake of folic acid, a B vitamin, before and during early pregnancy has been shown to prevent 50-70% of neural-tube defects. Increased NTD incidence has long been reported to occur more frequently among women of lower socioeconomic (SES). Since consumption of the folate-rich Mediterranean diet in Spain does not vary by socio-economic status (SES), we hypothesized that there would be no social class effect on NTD occurrence. Using data from a Spanish hospital-based birth defects registry, we studied the risk of Neural Tube Defects (NTDs) in 980 cases and 774 controls between 1980 and 2003. Our analysis showed that the risk of NTDs did not vary by SES. This finding suggests that increased access to folate and nutrition education might benefit women of lower SES in the US.