meningocele: a congenital anomaly of the central nervous system in which a sac protruding from the brain or the spinal meninges contains cerebrospinal fluid (but no nerve tissue)
birth defect: a defect that is present at birth
erythroblastosis fetalis: severe anemia in newborn babies; the result of Rh incompatibility between maternal and fetal blood; typically occurs when the child of an Rh-negative mother inherits Rh-positive blood from the father; can be diagnosed before birth by amniocentesis