The research is the first to show the benefits of breast milk for babies born weighing less than 2 pounds, 3 ounces. With medical advances, hospitals are saving more of these babies, some born more than three months early.
For these infants, brain development that normally would occur in the womb during the third trimester of pregnancy must occur in the neonatal intensive care unit of a hospital, said study co-author Dr. Betty Vohr of Brown Medical School.
Ingredients in breast milk, particularly fatty acids, seem to help the brain develop properly, she said.
Feeding breast milk to the smallest, sickest babies on the edge of viability could save schools money in special education services later, Vohr said.
The study appears in the July issue of Pediatrics, being released Wednesday. A separate study in the same issue showed that children breast-fed longer than three months were less likely to become bed-wetters later in childhood.
Researchers tracked 1,035 extremely low-birthweight infants born at 15 hospitals. About three-quarters of the babies received at least some breast milk in the hospital. One-quarter received only formula.
Even when the researchers took education and income into account, the breast milk babies scored higher on tests of mental development when they were 18 months old than the formula babies.
The more breast milk the babies consumed, the better they did on the tests. Breast milk had no effect on rates of cerebral palsy, blindness or hearing problems.
The American Academy of Pediatrics recommends that premature and other high-risk infants be fed breast milk. Some preemies can be fed at the breast, but the very early babies in the study hadn’t yet developed the ability to suckle. Some of their mothers pumped breast milk, which was then fed to the infants by tube or in a bottle.
Most infant formula is made from cow’s milk, said Dr. Sheela Geraghty, who directs a breast-feeding program at the Cincinnati Children’s Hospital Medical Center and was not involved in the study.
“We’re the only species on the planet that drinks another species’ milk,” Geraghty said. “Human milk is what these babies need.”