Growth & Development: The Growth of Low Birth Weight Preterm Infants

Low Birth Weight (LBW) preterm infants are generally defined as those born at 32 to 34 weeks gestation and weighing at least 1500 grams.

1. These infants grow well on their mother's own milk. The predominance of whey proteins in human milk is associated with less imbalance of plasma amino acids then a casein predominant formula. The bile salt stimulated lipase found in human milk and the organization of the human milk fat globule facilitiates the absorption of medium and long chain fatty acids by the premature infant ( Schanler, 1999-2 ).

2. They may have less increase in calcium and phosphorus than if they had remained in utero, but do not need calcium or phosphorus supplementation. They do need supplementation with Vitamin D and Iron.

3. The mother's preterm milk will change as her child grows and will become more like term milk as her child approaches term age (3 to 5 weeks after birth).

4. These infants may have immature suck and swallow until they reach about 34 weeks gestation, and may have difficulty breastfeeding.

5. The small size of their mouth may cause difficulty grasping the maternal nipple.

6. They may have temperature and respiratory instability.

7. Putting these infants to breast with associated skin to skin contact with mother (Kangaroo care) often allows them to tolerate breastfeeding better than bottle feeding due to increased warmth and oxygenation ( Meier, 1988 and Bier, 1997 ). Further work by Meier showed that premature infants sucking during bottle-feeding had more sustained interruptions of breathing than did premature infants suckling at the breast. This appears to be the mechanism of more normal oxygenation during breastfeeding ( Meier, 2001 ).

8. Small infants at the breast can regulate the flow of breast milk better than the flow of formula from a bottle (better tolerance) ( Meier, 1988 ).

9. Mothers may need to pump in addition to the baby suckling at breast to build up a good milk supply due to their infant's less effective suck.

10. The infant's overall growth is determined by nutritional intake, and the state of their health. Because breastfed preterm infants may have less infectious complications of prematurity, breastfeeding may enhance their growth ( Schanler, 1995 ).

11. Breastfeeding should be encouraged for these infants ( Schanler, 1995 ).

Guidelines for the transition of the premature infant from the NICU to home, "NICU Graduate Going Home" have been developed by the physicians of the Academy of Breastfeeding Medicine ( ABM, 2004-2 ).