ABSTRACT: Milk maturation from colostrum to mature milk occurs at rates that vary from mother to mother. The clinical significance of milk maturation rate is discussed here. Milk samples of 98 mothers were monitored in an observational study using the Maturation Index of Colostrum and Milk (MICAM). Samples were collected with each feeding during hospitalization, twice daily at home through day 7, and on days 14 and 28. Frequency and duration of early feeding were positively associated with milk maturation rates. An increased milk maturation rate was associated with an increased rate in infant weight gain at 28 days, lower transcutaneous bilimeter readings at 14 days and increased weeks of breastfeeding for those who weaned by 20 weeks. It is concluded from these associations that rapid milk maturation is desirable.