Six years ago, Sarah and Ross Gray were excited to be expecting twins, but the happy news turned to sorrow when they learned that one of the babies would not survive.

“We found out that one of them was healthy and one of them wasn’t,” Sarah told CBS News’ Weijia Jiang.

One baby had anencephaly, a serious birth defect that prevents the brain and skull from forming correctly. About three pregnancies in every 10,000 in the United States results in anencephaly, according to the CDC. And almost all babies born with the condition die shortly after birth.

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Faced with losing their newborn, the family looked for ways his short life could make a lasting difference.

The twins, Callum and Thomas, were born on March 23, 2010. Thomas only lived for six days.

“There was nothing we could do to save Thomas’s life, and I think once we were able to accept that and think, this is inevitable, but it doesn’t have to be unproductive. So maybe there is some good that can come,” their mom said.

A photo of Thomas Gray Courtesy Gray family

Thomas’ organs were too tiny to transplant so the Grays donated his liver, blood and eyes to researchers at three prestigious universities.

Dr. Arupa Ganguly, a professor of genetics at the Hospital of the University of Pennsylvania, in Philadelphia, studies eye cancer in children.

“The donation of the retina, which is impossible to get under normal circumstances, was very valuable,” Ganguly said. Their work with Thomas’ donated tissue could eventually help many other children.

Sarah Gray reached out to Dr. Ganguly to find out what had come of the donation, and last year, the Gray family visited her lab.

“This made a very nice human connection, which I think is everlasting for all of us,” said Ganguly.

Sarah also visited Harvard and Duke.

Research using Thomas’ tissue has been published in nearly two dozen academic articles.

“When we had him with us, we didn’t know the impact he was about to have. He’s an important baby,” said Sarah.

Sarah Gray makes emotional visit to the lab. Courtesy Gray family

Callum, now 6 years old, has a baby sister, Jocelyn. And Sarah works for the national tissue bank which facilitates one million transplants a year. She wrote a book about her experience, “A Life Everlasting: The Extraordinary Story of One Boy’s Gift to Medical Science.”

She said seeing the impact of her gift inspired her to help others make the same choice.