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J Obstet Gynecol Neonatal Nurs. 2000 Mar-Apr;29(2):145-52.

Differential effects of breast- and formula-feeding on preterm infants' sleep-wake patterns.

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Department of Family and Child Nursing, University of Washington, Seattle 98195-7262, USA.



To compare sleep-wake patterns of breastfed and formula-fed preterm infants.


Data were taken from an exploratory study of infant biorhythm maturation. Parents completed a 24-hour diary of infant Sleep, Awake, and Cry states and feedings, recorded at 30-minute intervals. Infant health data were collected from medical records and parents' reports.


Infants were studied in the home after discharge from a neonatal intensive-care unit.


The convenience sample included 12 breastfed and 25 formula-fed preterm infants (gestational age, 26-33 weeks; corrected postnatal age, 4-6 weeks). Groups were comparable in terms of gestational age, postnatal age, Apgar scores, maternal age, and home environment.


The 24-hour recording period was divided into day (0600-1800) and night (1800-0600). Study variables were Day, Night, and 24-hour Sleep, Awake, and Cry.


Breastfed preterm infants exhibited more Day Cry and 24-hour Cry than did formula-fed infants. Infants demonstrated a diurnal pattern in Cry, Awake, and Sleep. Breastfed preterm infants cried approximately 1 hour per day more than formula-fed infants.


Preterm breastfed infants experienced more cry than did formula-fed infants. The relationship between feeding method and sleep-wake pattern has implications for supporting lactation as well as for research design.

[Indexed for MEDLINE]

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