[Infant mortality and perinatal mortality in Poland in the eighties. II. Deaths by birthweight].

The dynamics of the changes in the level of the birthweight-specific infant mortality and perinatal mortality rates by age and cause during the eighties is presented. The strongest decline in the birthweight-specific infant and perinatal mortality rates is observed among the newborns weighing less than 2500 g. The level of the low birth weight (7.9% in 1989) and despite the decrease--the infant and perinatal mortality rates among the newborns weighing 1001-2500 g (100.5 and 109.4 respectively in 1989) and among the newborns weighing 601-1000 g (865.3 and 851.1 respectively in 1989) are high comparing to the developed countries.