Determine whether the use of vitamin/folate supplements around the time of conception reduces the risk of producing an infant with neural tube defects. This will be accomplished by a case-control study. The Epidemiology and Biometry Research Program (EBRP) of the National Institute of Child Health and Human Development (NICHD) will design a protocol for interviewing women who have produced a child with a neural tube defect and appropriate control subjects. The selected contractors will locate the aforementioned women, conduct the interviews, and transmit the data collected to the Data Coordinating Center.