A Review of the Literature Examining the Benefits and Challenges, Incidence and Duration, and Barriers to Breastfeeding in Preterm Infants

Jennifer Callen, RNC, MSC; Janet Pinelli, RNC, MSCN, DNS


Adv Neonatal Care. 2005;5(2):72-88. 

In This Article

Incidence and Duration of Breastfeeding for Preterm Infants

The initiation and duration of breastfeeding for preterm infants[2—13] are lower than for full-term infants. See Table 1 for studies from 1990 to 2001. Mothers and their preterm infants have significant difficulties in making the transition from expressing milk and gavage feeding to feeding at the breast.[83,109]

Study results examining the incidence and duration of breastfeeding in preterm infants are difficult to interpret. In studies examining term infants, breastfeeding incidence is defined as the percentage of infants breastfeeding at birth.[110—111] Because preterm infants begin feeding by gavage tube, the majority of studies examining preterm infants did not examine the incidence of breastfeeding. The definition of incidence in the National Surveys of Family Growth included infants who were breastfed at any time.[12] In contrast, the definition used by Ross Laboratories Mothers Surveys included only those breastfeeding at 1 week of age and beyond.[12] Despite the use of different definitions, the incidence of breastfeeding was similar; 33% and 38% respectively.[12]

The duration of breastfeeding preterm infants varies widely. The rate of breastfeeding at hospital discharge ranges from 49%2 to 91%; when exclusive breastfeeding is examined, the rate is 54%.[6] The mean PCA at hospital discharge for infants in both studies was not specified; based on the average gestational age at birth and the age of infants at hospital discharge, it appears as though infants in both studies were approximately 36 to 37 weeks PCA at hospital discharge.[2,6]

It is difficult to compare the duration of breastfeeding after hospital discharge as authors examine breastfeeding rates at 4 weeks,[3] 8 weeks,[6—8] and 12 weeks.[11] Finally, from the 13 studies examined, only 2 studies analyzed VLBW infants weighing < 1500 g.[2,11]

Although these studies provide useful preliminary information, a number of methodological problems decreases their validity both individually and collectively. Two studies collected data retrospectively, creating a potential recall bias.[1,2] Two other studies[4,13] did not report sample size, methods, or data collection and data analysis techniques, limiting the ability to determine the validity and reliability of the study results. These same studies concluded that the introduction of a breastfeeding protocol and support group increased the duration of breastfeeding; however, they provided no preintervention data.[4,10,13]

To eliminate bias and allow for replication, studies must clearly specify their sample size, methods, and data collection and data analysis techniques.[112] Future studies should use a prospective design and a control group to examine the impact of breastfeeding support and education programs.

Differences in breastfeeding definitions also make the results difficult to interpret. Studies that used the breastfeeding definitions proposed by Labbok and Krasovec113 (Fig 1) are comparable.[4,6—8,11] Studies that neglected to explicitly define breastfeeding[5,12,13] or specified their own definitions of breastfeeding[2,4,9,10] are not comparable. Consistent and valid definitions of breastfeeding are required to increase comparability of data collected from several countries or regions and to increase the usefulness and accuracy of this body of research.[113]

Labbok and Krasovec´s breastfeeding definitions. Reprinted with permission from Labbok M, Krasovec K. Toward consistency in breastfeeding definitions. Stud Fam Plann. 1990;21:226 –230.

The comparability of results between these studies was also confounded by the degree of prematurity of the infants. For example, infants had gestational ages ranging from 24 weeks11 to 37 weeks[5] and mean birthweights ranging from 1083[11] to 2590 g.[5] To provide more comparable results, studies must examine preterm infants of consistent gestational ages and weights or use stratification.


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