Perinatal mortality is one of the least understood areas of maternal and newborn health. Last week, the UK Confidential Enquiry into Maternal and Child Health (CEMACH) released figures from 2005 showing that perinatal mortality rates (defined as fetal death after 22 weeks' gestation or infant death within 7 days of birth) have not changed since the early 1990s. The same trend applies to many countries in the WHO European region.
Maternal risk factors for perinatal mortality are known. Those who are black, Asian, socially deprived, younger than 20 years or older than 40 years are most at risk, and yet the rate of perinatal mortality remains unacceptably high. The CEMACH report blames a lack of knowledge of the causes of death; more than half of the stillbirths they recorded were classified as “unexplained”. This ignorance stems from a lack of research—perinatal autopsy rates in the UK decreased from 58% in 1993 to 39% in 2005, and in 2006 there were twice as many research studies published on infant mortality than on perinatal death. Any research that is reported is obscured by country-specific definitions of perinatal mortality. Earlier this year, the US Centers for Disease Control and Prevention reported a 19% reduction in perinatal deaths between 1990 and 2003, but their definition of perinatal mortality included infant deaths up to 28 days after birth. It is futile to compare these statistics to those released by CEMACH this week. In 1982, the International Federation of Obstetrics and Gynecology agreed a weight-specific definition of perinatal mortality: the death of a fetus or newborn baby weighing more than 1000 g. The CEMACH report converts all of its current data to this standard to facilitate international comparison, but this is not replicated in analyses from the USA and many European countries.
Without a sustained and international effort to promote research and perinatal autopsies, the causes of these tragedies are likely to remain unknown, and the means to reduce perinatal mortality rates will continue to be elusive. Yet before these efforts can be of use, a global definition of perinatal mortality must be agreed, and adhered to.