Objective: To explore whether and how population based data froma regional qua lity control programme can be used to investigate the hypothesis that small for gestational age (SGA) very low birthweight infants (VLBW, < 1500 g) are at incre ased risk of death, severe intraventricular haemorrhage (IVH), and periventricul ar leucomalacia (PVL), but at decreased risk of respiratory distress syndrome (R DS). Methods: Analyses of population based perinatal/neonatal data (1991-96) fr om a quality control programme in Lower Saxony, Germany. After assessment of dat a validity and representativeness, exclusion criteria were defined: birth weight > 90th centile, severe malformations, siblings of multiple births, and gestatio nal age (GA) < 25 or > 29 weeks. Outcomes of interest were death, severe IVH, PV L, and RDS. Multivariable analyses were performed by Cox proportional hazard and logistic regression models. Results: Within the data validation procedure, on i ncrease in proportions of both VLBW (from 0.95%in 1991 to 1.11%in 1996; +17 %) and SGA (from 22.7%to 27.4%; +21%) infants became apparent (p < 0.05) . The study population consisted of 1623 infants (173 SGA). Mortality was 12.1 %(n = 196), with an adjusted hazard ratio for SGA infants of 2.54, 95%confide nce interval (CI) 1.70 to 3.79.Both groups were at similar risk of severe IVH (adjusted odds ratio 0.93, 95%CI 0.5 to 1.65) and PVL (1.54, 95%CI 0.78 to 2.87), but SGA infants had less RDS (0.57, 95%CI 0.35 to 0.93). Male sex , multiple birth, hypothermia ( < 35.5°C), and sepsis were associated with IVH and RDS. Infants admitted to hospitals with < 36 VLBW admissions/year had incre ased mortality (adjusted hazard ratio 1.56, 95%CI 1.12 to 2.18). Conclusions : SGA VLBW infants are at increased risk of death, but not of IVH and PVL, and a t decreased risk of RDS. That mortality is higher in smaller hospitals needs fur ther investigation. Objective: To explore whether and how population based data froma regional qua lity control program can be used to investigate the hypothesis that small for gestational age (SGA) very low birthweight infants (VLBW, <1500 g) are at incre ased risk of death, severe intraventricular haemorrhage (IVH), and periventricul ar leucomalacia (PVL), but at decreased decreased of respiratory distress syndrome (R DS). Methods: Analyzes of population based perinatal / neonatal data (1991-96) fr om a quality control program in Lower Saxony, Germany. After assessment of dat a validity and representativeness, exclusion criteria were defined: birth weight> 90th centile, severe malformations, siblings of multiple births, and gestage nal age (GA) <25 or> 29 weeks. Outcomes of interest were death, severe IVH, PV L, and RDS. Multivariable analyzes were performed by Cox proportional hazard and logistic regression models. Results: Within the data validation procedure, on icrease proportions of both VLB (From 0.95% in 1991 to 1.11% in 1996; + 17%) and SGA (from 22.7% to 27.4%; + 21%) infants became apparent (p <0.05). The study population consisted of 1623 infants Mortality was 12.1% (n = 196) with an adjusted hazard ratio for SGA infants of 2.54, 95% confidence nce interval (CI) 1.70 to 3.79.Both groups were at similar risk of severe IVH (adjusted odds ratio 0.93, 95% CI 0.5 to 1.65) and PVL (1.54, 95% CI 0.78 to 2.87), but SGA infants had less RDS (0.57, 95% CI 0.35 to 0.93) , and sepsis were associated with IVH and RDS. Infants admitted to hospitals with <36 VLBW admissions / year had incre ased mortality (adjusted hazard ratio 1.56, 95% CI 1.12 to 2.18). Conclusions: SGA VLBW infants are at increased risk of death , but not of IVH and PVL, and at decreased decreased risk of RDS. That mortality is higher in smaller hospitals needs fur ther investigation.