Adequacy of expressed breast milk for early growth of preterm infants

Abstract

Since the early years of caring for preterm infants it has been widely taught that breast milk is their food of choice. In Cardiff the milk bank at St. David's Hospital has made this teaching a reality for many years since sufficient amounts of expressed breast milk have usually been available for the city's preterm infants during the early weeks of life. Lately, however, this practice has been criticized because poor weight gain has been noted in many of these infants compared with those who have been fed on unmodified cows' milk formulae. Similar observations were made by earlier workers but these seem to have been viewed with little concern since the widespread belief of the superiority of breast milk for preterm infants continues. In recent years there has been considerable publicity given to the importance of early postnatal growth due to a growing body of evidence, mainly from animal studies, that early growth impairment might adversely affect later growth and mental development. The suspicion that breast milk was less able than cows' milk to maintain satisfactory growth in preterm infants prompted the present study which compares the early growth of preterm infants fed these two milks. Poor weight gain observed in preterm infants who were fed expressed breast milk compared with those fed a cows' milk formula prompted a detailed study of early postnatal growth. In preterm infants fed these two milks, 68 infants were divided into two categories by gestational age at birth (i) 28-32 weeks (n = 28), (ii) 33-36 weeks (n = 40). They were randomly allocated to a feed of expressed breast milk or a milk formula. Rates of weight gain, linear growth, and head circumference growth wwere evaluated over two periods: birth-1 month, 1-2 months. The younger group who were fed breast milk showed slower overall growth rates over the first month than those fed formula. In the second month, and for the older infants over both of the 2-monthly periods, growth rates were similar in the two feeding regimens. It is concluded that expressed breast milk is inadequate for the growth of very immature preterm infants during early postnatal life.