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Unstudied infants: outcomes of moderately premature infants in the neonatal intensive care unit
  1. G J Escobar1,2,
  2. M C McCormick3,4,
  3. J A F Zupancic4,
  4. K Coleman-Phox1,
  5. M A Armstrong1,
  6. J D Greene1,
  7. E C Eichenwald5,
  8. D K Richardson4
  1. 1Kaiser Permanente Medical Care Program, Division of Research, Perinatal Research Unit, Oakland, CA, USA
  2. 2Kaiser Permanente Medical Center, Department of Pediatrics, Walnut Creek, CA, USA
  3. 3Department of Society, Human Development and Health, Harvard School of Public Health, Boston, MA, USA
  4. 4Department of Neonatology, Beth Israel Deaconess Medical Center, Boston
  5. 5Harvard Medical School, Department of Newborn Medicine, Brigham and Women’s Hospital, Boston
  1. Correspondence to:
    Dr Escobar
    Kaiser Permanente Medical Care Program, Division of Research, Perinatal Research Unit, 2000 Broadway, 2nd floor, Oakland, CA 94612, USA; gabriel.escobar{at}


Background: Newborns of 30–34 weeks gestation comprise 3.9% of all live births in the United States and 32% of all premature infants. They have been studied much less than very low birthweight infants.

Objective: To measure in-hospital outcomes and readmission within three months of discharge of moderately premature infants.

Design: Prospective cohort study including retrospective chart review and telephone interviews after discharge.

Setting: Ten birth hospitals in California and Massachusetts.

Patients: Surviving moderately premature infants born between October 2001 and February 2003.

Main outcome measures: (a) Occurrence of assisted ventilation during the hospital stay after birth; (b) adverse in-hospital outcomes—for example, necrotising enterocolitis; (c) readmission within three months of discharge.

Results: With the use of prospective cluster sampling, 850 eligible infants and their families were identified, randomly selected, and enrolled. A total of 677 families completed a telephone interview three months after hospital discharge. During the birth stay, these babies experienced substantial morbidity: 45.7% experienced assisted ventilation, and 3.2% still required supplemental oxygen at 36 weeks. Readmission within three months occurred in 11.2% of the cohort and was higher among male infants and those with chronic lung disease.

Conclusions: Moderately premature infants experience significant morbidity, as evidenced by high rates of assisted ventilation, use of oxygen at 36 weeks, and readmission. Such morbidity deserves more research.

  • NICU, neonatal intensive care unit
  • PMA, postmenstrual age
  • assisted ventilation
  • outcomes
  • prematurity
  • morbidity
  • intensive care
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  • Published Online First 12 April 2006

  • Competing interests: none declared

  • Presented at a platform session at the May 2004 meetings of the Society for Pediatric Research in San Francisco, California, and at Bethesda, MD at the NICHD Workshop on Optimizing Care and Long-term Outcome of Near-term Pregnancy and the Near-term Newborn Infant in July of 2005.

  • D K Richardson is deceased.

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