Prematurity and the benefits of breast milk
Because the fetus grows far more rapidly in the third trimester than the term infant does in the first months of life, deprivation of critical nutrients in the early days of life affects the premature infant more significantly than it does the full-term infant. Prolonged hospitalization, invasive procedures, and an immature immune system provide fertile ground for infection. The premature infant's gastrointestinal system also is immature, increasing susceptibility to necrotizing enterocolitis (NEC). The optimal nutrition provided by breast milk provides both early and long-term protection against these and other threats.
Early benefits of breast milk include decreased incidence and severity of NEC and reduced likelihood of perforation and later stricture formation.1-3 Premature infants fed human milk have shorter hospitalizations than those receiving formula, probably because of decreased incidence for NEC and sepsis.1 These benefits increase with the quantity of breast milk a baby receives and with duration of feeding.
Long-term benefits of breast milk include protection against illness beyond weaning and decreased incidence of allergies. How much protection depends on the dose, duration, and exclusivity of breastfeeding.4 Breast milk also is associated with improved neurodevelopmental outcomes in premature infants, again with a dose-response relationship.5,6 Visual acuity may also be improved in preterm infants, possibly because of the lipid profile in breast milk.7
Maternal benefits. Pumping and breastfeeding improve the mother's postpartum physical recovery and are an important part of her psychological healing. Many mothers feel guilty for delivering prematurely. Providing breast milk restores to the mother a sense of competency and the recognition that she can protect, nurture, and nourish her infant. Another potential benefit is demonstrated in a large study published in 2002, that for every 12 months a woman breastfeeds, the chance of developing breast cancer decreases by more than 4%.8
Overcoming obstacles to breastfeeding
Centers vary greatly in the proportion of mothers of premature babies who provide breast milk to their infants during hospitalization and after discharge. A large multicenter study of more than 42,000 infants showed that fewer than half of neonatal intensive care unit (NICU) graduates received any breast milk by the time of discharge.9 The authors suggest that variables in the culture of individual sites highly influence these rates. In sites where use of breast milk was high, for example, physicians openly supported breastfeeding and breast milk production (see Table).
A mother's ability to provide her premature infant with breast milk may be limited by an inadequate milk supply or difficulties in transitioning to the breast.
Insufficient milk production. When she goes home, the mother who produces less than about 15 ounces of milk a day must use triple feeding—breastfeeding, followed by supplementation (most commonly with a bottle), followed by pumping. An inadequate milk supply makes it less likely the mother eventually will transition from bottle feeding to breastfeeding.
Impaired lactogenesis can have a preglandular, glandular, or postglandular cause.10Preglandular causes are associated with an unfavorable hormonal profile, which primarily reduces the action of prolactin or oxytocin (for example, because of a retained placenta). An example of a glandular cause would include breast surgery, fibrosis related to a history of sever mastitis or radiation therapy, or insufficient mammary glandular development. Postglandular impaired lactogenesis is related to any situation that results in ineffective or infrequent milk removal beginning on the first postpartum day. Most impaired lactogenesis is of this latter type and is likely to be preventable.
For the mother who delivers prematurely, postglandular impaired lactogenesis represents a failure to overcome 3 pumping hurdles: delayed initiation of pumping, infrequent pumping, and inadequate emptying of the breasts.
These hurdles can be conquered in several ways:
- Begin frequent pumping on day 1.
- Be alert to causes of possible pumping difficulties, such as breakdown in mother's schedule, pump problems (inadequate pump or poor-fitting shields, outflow obstruction (engorgement, mastitis), or impaired let-down.
- Use early nonpharmacologic interventions, such as skin-to-skin care, nonnutritive sucking at the breast, pumping at the bedside and the use of trophic feeds.
- Consider early use of galactogogues (agents that increase prolactin) such as dopamine inhibitors.
- Have mothers vigilantly watch for mastitis and, if it occurs, treat promptly.
Failure to transition to the breast. Transitioning to the breast is important because mothers who are not exclusively breastfeeding at 1 month after discharge are unlikely to continue providing human milk to their babies.11 The strategy for reaching this goal is fourfold:
- Start breastfeeding early. Keep in mind that the premature baby lacks normal final trimester growth and experience. She needs to learn how to latch onto the breast, how to suck effectively, and how to coordinate sucking, swallowing, and breathing.
- Avoid caloric deprivation, a serious and common problem in NICUs frequently related to unnecessary volume restriction.12,13
While today, fewer preterm infants develop chronic lung disease than in the past, the practice of restricting feeding volumes to 150 mL/kg/day has been slow to change, despite recommendations to feed extremely low birth-weight infants 180 mL/kg/day.14
Counterproductive behaviors, such as crying, excessive pacifier use, and bottle feeding when energy-saving gavage feeding is more appropriate, may contribute to the "content to starve" behavior, so well-recognized in underfed term infants, who fall asleep at the breast because of exhaustion rather than satiety.15
- Abbreviate hospitalization as much as possible; one study demonstrated that each additional week of hospitalization reduced the odds of the infant's transitioning to direct breastfeeding by 14%.16 Achieving breastfeeding competency at the expense of prolonging the infant-mother separation may be counterproductive.
- Define a rational approach to bottle feeds, based on maternal milk volume, the baby's competency at the breast, and gestational age. If mothers are high producers and therefore are more likely to eventually transition to breastfeeding, it makes sense to delay introducing bottles until the infant establishes some degree of breastfeeding competency. In contrast, infants of mothers whose production has plateaued at low levels may benefit from earlier bottle introduction, in an effort to decrease the transition time to full oral feeds.17
Most mothers who have depended on pumping to maintain milk production cannot immediately begin exclusive breastfeeding when they leave the hospital. These mothers should start with time-limited breastfeeding—say 30 minutes—followed by liberal supplementation, followed by pumping (yes, triple feeding). Once the baby shows good weight gain, Mom can alternate between time-limited breastfeeding followed by supplementation and time-limited breastfeeding followed by pumping. With continued good infant weight gain, she can move on to unlimited demand breastfeeding, gradually tapering the pumping.
- Schanler RJ, Shulman RJ, Lau C. Feeding strategies for premature infants. Beneficial outcomes of feeding fortified human milk versus preterm formula. Pediatrics 1999;103:1150-57.
- Lucas A, Cole TJ. Breast milk and neonatal necrotizing enterocolitis. Lancet 1990;336:1519-23.
- Covert RF, Barman N, Domanico RS, et al. Prior enteral nutrition with human milk protects against intestinal perforation in infants who develop necrotizing enterocolitis. Pediatr Res 1995;37:305A.
- Heinig MJ. Host defense benefits of breastfeeding for the infant: effect of breastfeeding duration and exclusitivity. Pediatr Clin North Am 2001;48:105-23.
- Anderson JW, Johnstone BM, Remley DT. Breastfeeding and cognitive development: a meta-analysis. Am J Clin Nutr 1999;70:525-35.
- Lucas A, Morely R, Cole TJ, et al.Breast milk and subsequent intelligence quotient in children born preterm. Lancet 1992;339:261-64.
- Carlson SE, Ford AJ, Werkman SH, et al. Visual acuity and fatty acid status of term infants fed human milk and formula with and without docosahexaenoate from egg yolk lecithin. Pediatr Res 1996;39:882-88.
- Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50,302 women with breast cancer and 96,973 without the disease. Lancet 2002;360:187-95.
- Powers H, Clark RH, Bloom BT, et al. Site variation in rates of breastmilk feedings in neonates discharged from intensive care units. Academy of Breastfeeding Medicine News and Views 2001;7:37. Abstract.
- Neville MC, Morton J, Umemura S.Lactogenesis: the transition from pregnancy to lactation. Pediatr Clin North Am 2001;Feb;48:35-52.
- Bier JA, Oliver T, Ferguson AE, et al. Human milk improves cognitive and motor development of premature infants during infancy. J Hum Lact 2002;18:361-67.
- Clark RH, Thomas P, Peabody J. Extrauterine growth restriction remains a serious problem in prematurely born neonates. Pediatrics 2003;111:986-90.
- Colsen IE, Richardson DK, Schmide CH, et al. Intersite differences in weight growth velocity of extremely premature infants. Pediatrics 2002;110:1125-32.
- Hay WW, Lucas A, Heird WC, et al. Workshop summary: nutrition of the ELBW infant. Pediatrics 1999;104:1360-68.
- Habbick BF, Gerrard JW. Failure to thrive in the contented breast-fed baby. Can Med Assoc J. 1984;31:765-68.
- Smith MM, Durkin M, Hinton VJ, et al. Initiation of breastfeeding among mothers of very low birth weight infants. Pediatrics 2003;111:1337-42.
- Simpson C, Schanler RJ, Lau C. Early introduction of oral feeding in preterm infants. Pediatrics 2003;110:517-22.