Moderately preterm infants and determinants of length of hospital stay.

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 (> or = 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.