Spina bifida (Latin for “split spine”) is a neural tube defect (NTD) that occurs during the first month of pregnancy when the spine and spinal cord do not form properly. It is a congenital condition where the bony arches of the vertebrae fail to close completely, potentially exposing the spinal cord or meninges.

Spina bifida is a neural tube defect. The neural tube is the embryonic structure that eventually develops into the baby's brain, spinal cord, and the tissues that enclose them. Ideally, this tube forms and closes by the 28th day after conception. In cases of spina bifida, a portion of the neural tube fails to develop or close properly, resulting in defects in the spinal cord and the bones of the spine.