From February 2003 to December 2010, researchers of the Management of Myelomeningocele Study, or MOMS, clinical trial compared the safety and efficacy of different treatments for a specific type of spina bifida, called myelomeningocele. Myelomeningocele, the most frequent and severe form of spina bifida, is a condition in which the bony spinal column does not develop correctly, which causes an opening of the spine, exposure of the spinal cord, and formation of a small sac containing cerebrospinal fluid. Myelomeningocele affects 3.4 infants per 10,000 live births in the United States and is fatal in ten percent of affected infants. Investigators in the MOMS trial aimed to find a more successful treatment for myelomeningocele through different types of surgery. To accomplish that, they performed prenatal, or in utero, and postnatal repair operations in their study. The MOMS researchers concluded that prenatal repair improved motor and neurologic outcomes, such as the ability to activate and coordinate the muscles and limbs, and reduced the risk for fetal death.