Folic Acid and Pregnancy.

Despite decades of research recommending pregnant women take folic acid supplements in order to prevent spina bifida and other neural tube defects, only 31% of pregnant women in the United Kingdom (UK) do. Additionally, among women who had previously given birth to a baby with a neural tube defect, only 51% took a folic acid supplement during subsequent pregnancies. In the United States, Australia, and 74 other countries, some grain-based foods are fortified with folic acid in hopes of reducing the risk of these types of birth defects.
PLOS ONE, February 2014