Perinatal Period: its the rate from the moment
when fetus reach 1000 grams (equal 28 weeks of
gestation) to the 28th day of postnatal life.

Fetal death: a fetus over 500 grs or more than 20
weeks of gestation. For international comparisions,
we take into account only fetus >1000 grs.

Early Neonatal Death: a newborn died up to the
7 day of life (until 168 complete hours)

Late Neonatal Death: a newborn died from 7
complete days to 28 days of life

Low birth weight: a newborn < 2.500 grams of
body weight.

Very Low Birth Weight: a newborn < 1.500
grams of body weight and >1000

Extreme Low Birth Weight: A newborn <1000
grams

Abortion: a product of gestation < 500 grams or
20 weeks of gestation