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Moderately preterm infants and determinants of length of hospital stay
  1. M Altman1,
  2. M Vanpée2,
  3. S Cnattingius3,
  4. M Norman1
  1. 1
    Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
  2. 2
    Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
  3. 3
    Department of Medical Epidemiology and Biostatistics and Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to Dr Maria Altman, Department of Clinical Science, Intervention and Technology, Division of Pediatrics Karolinska Institutet, B57 Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden; maria.altman{at}


Background: Moderately preterm infants account for a large proportion of admissions and bed-days in neonatal units (NU). Management of these infants varies and determinants of length of stay are poorly studied.

Objective: To determine postmenstrual age at hospital discharge for moderately preterm infants and its relation to perinatal risk factors and to organisation of care.

Methods: Population-based cohort including 2388 infants, born in 2004–2005 with a gestational age (GA) of 30–34 weeks and admitted to 21 NU reporting to the Swedish perinatal register. Main outcome: postmenstrual age (PMA) at hospital discharge to home.

Results: Mean PMA at hospital discharge was 36.9 (1.7) weeks. High (⩾35 years) maternal age, multiple birth, small for gestational age, respiratory distress syndrome, infection, hypoglycaemia and hyperbilirubinaemia were significantly associated with higher PMA at discharge, but could only explain 13% of the variation in PMA at discharge. Mean PMA at discharge differed by up to 2 weeks between hospitals. Infants treated at NUs without fixed discharge criteria had 4.7 days lower PMA at discharge and infants receiving domiciliary care had 9.8 days lower PMA at discharge. Breastfed infants also had lower PMA at discharge (mean 2.7 days lower) than those not breast fed, partly explained by lower morbidity in the breastfed infants.

Conclusions: Perinatal risk factors have small overall impact on length of hospital stay in moderately preterm infants. Organisation of care is probably an important factor. The number of bed-days differs significantly between centres, which may have effects on quality of care and health economy.

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  • Funding The study was supported by The Swedish Order of Freemasons and Karolinska Institutet Research Foundations.

  • Competing interests None.

  • Provenance and Peer review Not commissioned; externally peer reviewed.

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