Moderately preterm infants and determinants of length of hospital stay

Maria Altman ^1*, Mireille Vanpée ², Sven Cnattingius ³ and Mikael Norman ¹

¹ Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
² Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
³ Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden

^* To whom correspondence should be addressed. E-mail: maria.altman{at}ki.se.

Accepted 13 May 2009

Abstract

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 organization of care.

Methods: Population-based cohort including 2,388 infants, born in 2004-2005 with a gestational age (GA) of 30-34 weeks and admitted to 21 neonatal units (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, hypoglycemia and hyperbilirubinemia 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 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 breastfed, 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. Organization of care is likely an important factor. The number of bed-days differs significantly between centers, which may have effects on quality of care and health economy.