The study included 77 preterm infants. The researchers retrospectively looked to see how much breast milk those babies had received while being cared for in the NICU. Then, the researchers conducted brain scans on those infants at about the time each would have been born had the babies not arrived early. All of the babies were born at least 10 weeks early, with an average gestation of 26 weeks, or about 14 weeks premature. Because they are still developing, preemies typically have smaller brains than full-term infants.