High glycemic load was previously thought to increase risk of neural tube defects after California researchers found that there appeared to be an association with maternal diets high in sugar in their state (1). However, the more recent National Birth Defects Prevention Study has found that the association does not exist among national population and other regions in the country (1). It is unclear why this is the case (1).
1. Shaw GM, Carmichael SL, Laurent C, Siega-Riz AM. Periconceptional glycaemic load and intake of sugars and their association with neural tube defects in offspring. Paediatr Perinat Epidemiol 2008;22:514-9.