Use of classification of primary obstetric factors in perinatally related mortality surveillance.

The use of a classification of the primary obstetric factors leading to death for all fetal and neonatal losses that occurred between 20 weeks gestation and 28 days after birth is described. This is defined as the 'total perinatally related loss', and is compared with the information obtained if enquiry is limited to the traditional 'perinatal' period, from 28 weeks gestation to 7 days after birth. Both centre-based data for Queen Mary Hospital, Dunedin, and population-based data for the geographic area of the Otago Hospital Board for the four year period from September 1982 until August 1986 are reported. Spontaneous prematurity was the major factor responsible for these deaths, and its importance would not have been appreciated if the perinatal period alone had been analysed. The need for standardised classification of perinatally related deaths for epidemiological monitoring is discussed.