Almost 90% of babies born with this type of spina bifida have hydrocephalus, excess brain fluid.

CNN: Study: Major benefits for spina bifida surgery in the womb

"The reduced risk of hydrocephalus is by the far the biggest benefit of this surgery, " said Dr .

CNN: Study: Major benefits for spina bifida surgery in the womb

Giffords had hydrocephalus after she was shot, a condition where an excess of cerebral-spinal fluid puts pressure on the brain.

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Before the onset of his disease, a rare incurable neurological disorder called normal pressure hydrocephalus, he was six-foot four and 200 pounds.

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Hallman said she decided to have the surgery on her unborn son when she learned he was less likely to develop the common complication hydrocephalus, water on the brain.

CNN: Study: Major benefits for spina bifida surgery in the womb