Definitions

The World Health Organization (WHO), in recognizing the importance of international comparison of perinatal and neonatal mortality, coordinates the compilation of health statistics and encourages member countries to rely on the same definitions when comparing the statistics. However, there remain slight differences in the definitions of perinatal mortality between some countries, reflecting the definition of viability and resources in the individual countries.

The definitions are drawn from the 10^th edition of the International Classification of Diseases (ICD-10). The key definitions are:

In the UK the definitions are different, reflecting the survival rates and concept of viability. The present legal definitions that apply to England and Wales are as follows:

In Australia and New Zealand, stillbirth is defined as ‘Death prior to the complete expulsion or extraction from its mother of a product of conception of 20 or more completed weeks of gestation or of 400 g or more birth weight where gestation is not known. The death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles’.

Mortality rates

The current definitions are as follows:

Incidence

Perinatal mortality rates vary widely: both between different countries and within different regions of the same country. In spite of initiatives in many countries to improve maternal and child health, there remains a significant disparity between developed countries and the developing countries.

WHO publishes global estimates on perinatal mortality rates by level of development and geographical regions. For comparison, the regions are divided into the ‘More developed, Less developed and Least developed’ with figures demonstrating a stark contrast between the regions (Table 5.1). In countries where no data collection takes place, models are produced to estimate mortality based on demographic and health surveys conducted by several agencies. Worldwide, there are over 6.3 million perinatal deaths annually, almost all of which occur in developing countries, and 27% occurring in the least developed countries alone, i.e. the sub-Saharan regions of central Africa. In developing countries, the PNMR is five times greater than in developed countries; in the least developed countries it is six time higher. It is highest in Africa, with 62 deaths per 1000 births, especially in middle and western Africa, with rates as high as 76 per 1000 births. The perinatal mortality rate in Asia is 50 per 1000 total births, with a peak of 65 per 1000 in South-central Asia.

Developed countries (Western Europe, North America, Japan, Australia and New Zealand) have seen a steady fall in the PNMR over the last 30 years. In the UK, the Centre for Maternal and Child Enquiries (CMACE) publishes annual perinatal reports and showed a statistically significant downward trend in the perinatal mortality rate, from 8.3 in 2000 to 7.5 per 1000 total births in 2008. This is due to both a statistically significant decrease in the early neonatal mortality rate (from 2.9 in 2000 to 2.5 in 2008 per 1000 live births) and a statistically significant decrease in the stillbirth rate ( from 5.4 to 5.1 per 1000 live births, respectively) (Fig. 5.1).

The reasons for this improvement include:

Sociodemographic factors and perinatal mortality

Factors that are known to affect perinatal mortality in the UK and Australia include the sociodemographic characteristics of the mother such as maternal age, deprivation, ethnicity (Table 5.2). Smoking also has a significant adverse effect on birth weight and perinatal mortality.