A mother-infant neonatal unit was established in 1979 at Tallinn Children's Hospital in Estonia to provide medical and nursing care to newborn and premature babies and their mothers. Its leading principles are 24-hour care by the mother, minimal use of technology, and little contact between the baby and medical and nursing staff. The unit was based on a conceptual model of the "psychological and biological umbilicus," which proposes that this connection binds the mother and infant together during the early weeks of life. Separation of mother and baby disrupts this important tie and may have adverse consequences for both. This paper presents data comparing weight gain during the first 30 days of life for a group of 159 preterm and full-term infants who were admitted to the unit between 1988 and 1989. Eighty-seven infants were cared for by their mothers, and 72 by nurses because their mothers were unwilling or unable to stay with the infants in the hospital. The holistic, humanistic approach used in the unit represents a truly baby-friendly hospital.