It was a new mother’s nightmare that inspired Lupita Carral to donate her extra breast milk to Texas Children’s Hospital. Six years ago, when her first daughter was only 3 days old, Carral found herself looking through the windows of the Neonatal Intensive Care Unit, where her tiny child was hooked up to IVs and feeding tubes. The infant was born with intestinal malrotation, and it took two days of complicated surgery and weeks in the hospital before doctors could be confident that the “miracle baby” would survive.

In July 2011, Carral gave birth to her third child at Texas Children’s, even though the family had since moved to South Florida. By coincidence, the hospital was beginning to accept donations of human breast milk for its own milk bank that week, and Carral, 30, became the first donor. She said she gave “four or five gallons” in total, enough to feed a baby for more than three months.

“People don’t realize that every baby born healthy is a miracle, but once you have a child who has problems, you understand that nothing is for sure,” Carral said from her Coral Gables home , while her three children played quietly in the next room. “I wanted to donate because I knew I had enough milk for my baby, and I realized that not everyone does.”

Almost all doctors agree that mother’s milk is the best option for full-term infants, and many are now beginning to accept human breast milk as the best option for babies born prematurely. The default option for feeding preterm infants — whose tiny bodies can’t handle large volumes of liquid — used to be a high-caloric formula with a concentration of protein and nutrients. Studies show that formula-fed babies do grow more quickly in the short term, but also have a higher risk of developing certain immune system and intestinal problems.

“Human milk is medicine. It’s nutritious and extremely beneficial to babies,” said Dr. Stephen Welty, chief of neonatology at Texas Children’s. “It’s so much more dangerous to give formula, that we’ll get to the point where parents will have to sign informed consent to give formula to premature babies.”

Now, a year after Carral made the first donation, more than 70 mothers have donated their extra breast milk, which has helped nourish 350 infants. The hospital has 8,000 ounces available and uses an average of 25 bottles, or 100 ounces, a day.

The milk is frozen and shipped to Prolacta Bioscience, a California-based company that tests and pasteurizes pooled donations. The human milk product, standardized with 20 calories per ounce, is sent back to the hospital where it is available for every baby in the Neonatal Intensive Care Unit. The company also makes a more concentrated human-milk-based product that has up to 28 calories per ounce, designed especially for preterm or infants with low weight.

Hospitals all over the country are beginning to stock human breast milk. The three children’s hospitals in South Florida — Holtz/Jackson, Miami Children’s and Joe DiMaggio/Memorial — don’t have their own milk banks, but they do have human breast milk on hand from outside sources.

There are 13 nonprofit milk banks in the United States and Canada registered with the Human Milk Banking Association of North America (HMBANA). Most South Florida hospitals get their donor milk from WakeMed Mothers’ Milk Bank in North Carolina or Mothers’ Milk Bank in Austin, Texas.