What type of inheritance is involved in spina bifida?

Multifactorial: Isolated spina bifida (myelomeningocele) is a neural tube defect along with anencephaly that exhibits multifactorial determination--a combination of many genes and in utero environmental factors that cross a threshold to produce the defect. A couple having a child with spina bifida or anencephaly has a ~2% risk for each future pregnancy, a risk decreased by preconception folic acid.

Dominant or not: Some hereditary forms are dominant, meaning only one parent needs to be affected to pass the condition to offspring. Other forms are recessive, meaning both parents have to contribute defective genetic material. Some genetic defects require a little "help" from factors such as maternal Folic Acid deficiency or "teratogenic" drugs. Consult obstetrician about medication usage, including otc ones.