title: Obstetrical volume and early neonatal mortality in preterm infants.
abstract: OBJECTIVE
  Regionalised perinatal care with antenatal transfer of high risk pregnancies to Level III centres is beneficial. However, levels of care are usually not linked to caseload requirements, which remain a point for discussion. We aimed to investigate the impact of annual delivery volume on early neonatal mortality among very preterm births.
  
  
  METHODS
  All neonates with gestational age 24-30 weeks, born 1991-1999 in Lower Saxony were included into this population-based cohort study (n = 5,083). Large units were defined as caring for more than 1,000 deliveries/year, large NICUs as those with at least 36 annual very low birthweight (<1,500 g, VLBW) admissions. Main outcome criterion was mortality until day 7. Adjusted Odds Ratios (adj. OR) and 95% confidence intervals (CI) were calculated based on generalised estimating equation models, accounting for correlation of individuals within units.
  
  
  RESULTS
  Within the first week of life, 20.6% of all neonates deceased; 10.2% were stillbirths, 3.7% died in the delivery unit, and 6.7% in the NICU. The crude OR for early neonatal mortality after having been delivered in a small delivery unit (excluding stillbirths) was 1.36 (95%CI 1.04-1.78; adj. OR 1.16 (0.82-1.63)). It increased to 1.96 (1.54-2.48; adj. OR 1.21 (0.86-1.70)) after the inclusion of stillbirths.
  
  
  CONCLUSIONS
  This study has shown a slight, but non-significant association between obstetrical volume and early neonatal mortality. In future studies the impact of caseload on outcome may become more evident when referring to high-risk patients instead of to the overall number of deliveries.
authors: Department of Epidemiology, Public Medicine and Healthcare Systems Research, Hannover Medical School, Carl-Neuberg-Str. 1, OE 5410, 30625 Hannover, Germany. bartels.dorothee@mh-hannover.de
authors: Dorothee B
authors: DB
authors: Bartels
authors: Paul
authors: P
authors: Wenzlaff
authors: Christian F
authors: CF
authors: Poets
mesh_terms: D015331:Cohort Studies; D019992:Databases as Topic; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007226:Infant Mortality / Q000639:trends*; D007231:Infant, Newborn; D008297:Male; D009775:Obstetrics and Gynecology Department, Hospital / Q000706:statistics & numerical data*; D016017:Odds Ratio; D047928:Premature Birth