This trial is testing a new minimally invasive surgery to fix a spinal defect in unborn babies. The surgery uses tiny tools and cameras inserted through small openings, aiming to reduce risks for both mother and baby. It targets pregnant women whose fetuses have been diagnosed with myelomeningocele (MMC), a severe form of spina bifida. This new treatment technique allows early closure of the spinal defect to prevent potential neurological and psychomotor complications.