Neonatal mortality rate: The number of children under 28 days of age who die, divided by the number of live births in that year.

Perinatal mortality (PNM) refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate.Variations in the precise definition of the perinatal mortality exist, specifically concerning the issue of inclusion or exclusion of early fetal and late neonatal fatalities. The World Health Organization defines perinatal mortality as the "number of stillbirths and deaths in the first week of life per 1,000 total births, the perinatal period commences at 28completed weeks (196 days) of gestation, and ends seven completed days after birth",but other definitions have been used.

The UK figure is about 8 per 1,000 and varies markedly by social class with the highest rates seen in Asian women. Globally, an estimated 2.6 million neonates died in 2013 before the first month of age down from 4.5 million in 1990