"[2] 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 22 completed weeks (154 days) of gestation,[3] and ends seven completed days after birth",[4] but other definitions have been used.

[5] The UK figure is about 8 per 1,000 and varies markedly by social class with the highest rates seen in Asian women.

Neonatal mortality refers to death of a live-born baby within the first 28 days of life.

Probiotic supplementation of preterm and low birthweight babies during their first month of life can reduce the risk of blood infections, bowel sickness and death in low- and middle-income settings.