OBJECTIVES
When you have completed this unit you should be able to:
- Define perinatal mortality rate.
- List the primary causes of perinatal death.
- Define the stillbirth and early neonatal mortality rates.
- Understand the importance of knowing the stillbirth and early neonatal mortality rates.
- List the final causes of early neonatal death.
- Calculate the stillbirth to early neonatal death ratio.
- Define the neonatal care index.
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COPYRIGHT
All rights reserved. No part of this Perinatal Education Programme may be altered in any way
without the written permission of the editorial board of the Perinatal Education Trust.
To facilitate the improvement of perinatal care, the Programme may be reproduced for teaching
purposes provided due acknowledgement is given and the material is not sold for financial profit.
While the advice and information in the Programme is believed to be accurate, the editorial board cannot accept responsibility or liability for any errors or omissions that may have been made.
ISBN 0 7992 2141 4
PERINATAL MORTALITY
48-1 WHAT DOES PERINATAL MEAN?
Perinatal means "around the time of birth". Perinatal usually applies to the last months of pregnancy and the first week after delivery.
48-2 WHAT IS A PERINATAL DEATH?
Perinatal deaths are made up of infants that are born dead plus infants that are born alive but die within the first 7 days after delivery, i.e. stillbirths and early neonatal deaths.
A detailed definition of stillbirth and early neonatal death will be given and discussed later in this unit.
| PERINATAL DEATHS INCLUDE BOTH STILLBIRTHS AND EARLY NEONATAL DEATHS |
48-3 WHAT IS THE WEIGHT CUT OFF FOR PERINATAL DEATHS?
In industrialised (developed) countries, all infants weighing 500 g or more are included in the definition of perinatal deaths. However, in many poor countries, only infants weighing 1000 g or more are included, as infants that are born alive, but weigh less than 1000 g, usually do not survive.
Therefore, in many hospitals small infants are not weighed and simply are regarded as miscarriages, especially if they are not born in a labour ward. As a result, these infants are not counted as perinatal deaths. This practice of excluding infants below 1000 g may have a marked influence on the perinatal information being collected.
In South Africa, every effort should be made to include all infants weighing 500 g or more as many very small infants can survive with good basic care. To avoid confusion, it is important when discussing perinatal deaths to state whether the perinatal deaths include infants of 500 g or more, or only infants of 1000 g or more.
| ALL LIVEBORN AND STILLBORN INFANTS WEIGHING 500 G OR MORE AT BIRTH SHOULD BE INCLUDED WHEN PERINATAL DATA IS RECORDED |
*** The perinatal period is strictly defined from the beginning of fetal viability until the end of the sixth day after birth. Defining fetal viability is difficult as it depends on the gestational age and the special care facilities available. Therefore, it is easier to use birth weight to define viability. In industrialised countries, infants may survive from 22 weeks gestation (500 g) while in developing countries infants are only expected to survive from 28 weeks (1000 g).
48-4 WHAT IS THE PERINATAL MORTALITY RATE?
The perinatal mortality rate (PNMR) is the number of stillbirths plus the number of early neonatal deaths per 1000 total deliveries. Note that the perinatal mortality rate is expressed per 1000 TOTAL births (i.e. stillbirths and livebirths).
| THE PERINATAL MORTALITY RATE IS THE NUMBER OF STILLBIRTHS PLUS EARLY NEONATAL DEATHS PER 1000 TOTAL BIRTHS |
48-5 HOW IS THE PERINATAL MORTALITY RATE CALCULATED?
The perinatal mortality rate is determined over a specific time period and calculated as follows:
Number of stillbirths + number of early neonatal deaths x 1000
The number of liveborn + the number of stillborn infants
For example, in a health care region there were 5000 deliveries in a year. There were 4800 livebirths, 200 stillbirths and 50 early neonatal deaths (i.e. 250 perinatal deaths). Therefore, the annual perinatal mortality rate for that region is:
250 x 1000 = 250 000 = 50/1000
4800 + 200 5000
48-6 WHAT IS THE PERINATAL MORTALITY RATE IN INDUSTRIAL COUNTRIES?
Most industrialized countries (and affluent communities in poor countries) have a perinatal mortality rate of about 10/1000 for infants weighing 500 g or more.
48-7 WHAT IS THE PERINATAL MORTALITY RATE IN POOR COUNTRIES?
In poor (developing) countries the perinatal mortality rate is at least 70/1000 for infants weighing 500 g or more. This is about seven times higher than that in industrialised countries. In some poor African countries, the perinatal mortality rate is as high as 300/1000.
48-8 WHAT IS THE PERINATAL MORTALITY RATE IN SOUTH AFRICA?
As representative perinatal mortality data are not available for all regions of South Africa, the exact perinatal mortality rate is not known. However, information from many sites suggest that the overall perinatal mortality rate in South Africa, for infants of 500 g or more, is approximately 55/ 1000. This varies widely between different areas from 35 /1000 in metropolitan areas, such as Cape Town, to over 100/1000 in some poor, rural areas.
The perinatal mortality rate for most of South Africa is, therefore, typical of a developing country while the rate in metropolitan regions is still about three times higher than that of industrialised countries.
| THE PERINATAL MORTALITY RATE IN SOUTH AFRICA, FOR INFANTS WEIGHING 500 G OR MORE, IS ABOUT 55/1000 WHICH IS SIMILAR TO MANY OTHER POOR COUNTRIES |
*** If only infants weighing 1000 g or more are included, the perinatal mortality rate in industrialised countries is about 7/1000 while that in poor countries is about 50/1000. Therefore, the perinatal mortality rate is reduced by about a third. As a result, the perinatal mortality rate in South Africa for infants of 1000 g or more is probably 33/1000.
48-9 WHY IS THE PERINATAL MORTALITY RATE IMPORTANT?
Because it reflects the level of health in pregnant women and their infants, as well as the standard of health care provided. The perinatal mortality rate is also one of the best indicators of the socioeconomic status of a community, region or country. As the standard of living of a region improves, the perinatal mortality rate falls. Following the perinatal mortality rate over a number of years gives a good idea of the progress of a community.
Communities with a high perinatal mortality rate also have a high maternal mortality rate as both reflect poor living conditions and inadequate health care services. In South Africa, there are about 27 perinatal deaths for each maternal death.
| THE PERINATAL MORTALITY RATE REFLECTS THE HEALTH OF A COMMUNITY |
The perinatal mortality rate can be used to identify problem areas where health authorities need to turn their attention.
48-10 HOW ARE PERINATAL DEATHS CLASSIFIED?
Perinatal deaths can be classified by their primary causes, i.e. the underlying clinical (obstetrical) problem during pregnancy or delivery which resulted in, or was associated with, either a stillbirth or an early neonatal death. If this problem had not occurred the infants would probably have survived.
Primary causes are important because many of them can be avoided. Management protocols to reduce the risk of perinatal deaths are usually aimed at preventing or treating these causes.
The primary causes of stillbirth and early neonatal death are very similar and, therefore, best considered together.
| THE PRIMARY CAUSE OF PERINATAL DEATH IS THE CLINICAL PROBLEM DURING PREGNANCY, LABOUR OR DELIVERY WHICH RESULTED IN THE DEATH
OF THE FETUS OR INFANT |
In addition to the primary cause of death, a final cause of death is used for neonatal deaths. The primary cause explains why the infant died while the final cause explains how the infant died.
48-11 WHAT ARE THE PRIMARY CAUSES OF PERINATAL DEATH?
In South Africa the common identifiable primary causes of perinatal death are:
- Spontaneous preterm labour.
- Intrapartum hypoxia.
- Antepartum haemorrhage.
- Hypertensive disorders.
- Infections.
- Fetal abnormalities.
- Intrauterine growth restriction.
- Trauma
- Maternal diseases.
A few perinatal deaths are due to less common conditions or problems not related to the pregnancy (e.g. motor car accident).
A detailed classification of the primary causes of perinatal deaths is given in unit 49.
48-12 CAN A PRIMARY CAUSE OF PERINATAL DEATH ALWAYS BE FOUND?
Unfortunately, the primary cause of many perinatal deaths remain unknown. In South Africa about 25% of perinatal deaths have no obvious primary cause. The more thoroughly a perinatal death is investigated, the more likely a primary cause will be found.
48-13 WHAT ARE THE COMMONEST PRIMARY CAUSES OF PERINATAL DEATH?
In South Africa (and many developing countries) the three most common primary causes of perinatal deaths are:
- Spontaneous preterm labour.
- Antepartum haemorrhage.
- Intrapartum hypoxia.
| PRETERM LABOUR, ANTEPARTUM HAEMORRHAGE AND INTRAPARTUM HYPOXIA ARE THE COMMONEST PRIMARY CAUSES OF PERINATAL DEATH |
48-14 WHY IS IT IMORTANT TO FIND A PRIMARY CAUSE OF PERINATAL DEATH?
Knowing the primary cause helps identify ways that the perinatal death may have been avoided.
| FINDING THE PRIMARY CAUSE OF PERINATAL DEATH HELPS TO IDENTIFY AVOIDABLE FACTORS |
48-15 WHAT CAUSES SPONTANEOUS PRETERM LABOUR?
Preterm labour (labour before 37 weeks gestation), which has not been induced artificially, may be caused by:
- Chorioamnionitis (often asymptomatic).
- Preterm prelabour rupture of the membranes (with or without obvious chorioamnionitis).
- Cervical incompetence.
Often no obvious underlying cause can be found.
48-16 WHAT ARE THE IMPORTANT CAUSES OF ANTEPARTUM HAEMORRHAGE?
- Placental abruption.
- Placenta praevia.
Placental abruption (with or without hypertension) remains a major cause of perinatal death even in
metropolitan areas where level III (tertiary) care is available. The cause of placental abruption remains unknown and it is largely unpreventable.
Placenta praevia is a far less common cause of perinatal death. However, every effort must still be made to diagnose placenta praevia early and manage it correctly.
48-17 WHAT ARE THE IMPORTANT CAUSES OF INTRAPARTUM HYPOXIA?
- Labour related, especially prolonged labour, cephalopelvic disproportion and a hypertonic uterus.
- Cord prolapse.
Except with cord prolapse, intrapartum hypoxia is almost always the result of uterine contractions, especially if the uterus does not relax normally between regular contractions. Intrapartum hypoxia presents with signs of fetal distress during labour. The early diagnosis and correct management of fetal distress and prolonged labour is very important.
| INTRAPARTUM HYPOXIA IS USUALLY DUE TO ABNORMAL UTERINE CONTRACTIONS |
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