Background Admission weight to neonatal intensive care units is used in several diagnosis related group (DRG) systems to assess reimbursement by health insurance programs for premature infants. Modifications of admission weights could significantly affect reimbursement in either direction.

Objective Whether the introduction of the German DRG system in 2004 influenced the distribution of admission weights of premature infants was investigated.

Design/methods All very low birthweight infants in the most heavily populated German federal state, North Rhine-Westphalia, born in 1999–2001 and 2004–2006, were investigated. Data were retrieved from the medical association of North Rhine-Westphalia on 13 180 very low birthweight infants (VLBW; birth weight <1500 g). These data included admission weight and gestational age.

Results In 2004–2006 compared to 1999–2001, there were significantly more infants with admission weights below 1000 g (2004–2006; 949–999 g: 460 infants, p=0.007) and 1500 g (2004–2006; 1449–1499 g: 815 infants, p=0.0019), and fewer infants with documented weights above these cut-off values (1999–2001; 1000–1049 g: 346 infants and 2004–2006; 1500–1549 g: 658 infants).

Conclusions The introduction of the DRG system in Germany has affected the distribution of admission weights of premature infants. Potential reasons for this effect including upcoding are discussed.