Background: In Australia there has been an increase in births and changes in demographics of the child-bearing population, however trends in infant hospital separations have not been investigated.   

Aim: To examine the trends in hospital admissions in the first year of life and identify whether changes in maternal and infant risk factors explain any changes.

Methods: Population based study of 788,798 liveborn infants with linked birth and hospital admission records in NSW from 2001-2009. Annual rate of infants admitted to hospital in the first year per 100 infants born were calculated. To examine whether changes in maternal and infant risk factors could explain changes in infant admission rate, a predictive model was developed, using logistic regression and data from 2001 and 2002, and applied to subsequent years data to predict number of infants admitted. 

Results: The infant hospital admission rate decreased by 10.5% from 18.4 infants admitted per 100 births in 2001 to 16.5 in 2009.  Fifty five per cent of this decrease could be explained by changes in factors that are associated with likelihood of hospitalisation; length of stay during the birth admission, maternal age and maternal smoking. The rate of admissions for jaundice and feeding difficulties increased significantly over the study period, while admissions for infections decreased.   

Conclusions: There has been a decrease in the rate of infants admitted to hospital in the first year of life, which can be partly explained by increasing maternal age, decreasing maternal smoking and a shift to shorter length of hospital stay at birth.  Improved maternal and neonatal care in hospital, increased postnatal support at home and the introduction of government policies may have contributed to reduced readmissions.  Analysis of the trends in health services utilisation can lead to improvements in health service delivery and efficient allocation of healthcare resources.