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3

Perinatal mortality

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Perinatal mortality

3-1 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.

3-2 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.

Perinatal deaths include both stillbirths and early neonatal deaths.

3-3 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 most developing countries the accurate gestational age of many small infants is not known. Therefore it is better to use birth weight than gestational age in defining perinatal deaths. The World Health Organisation (WHO) recommends that all births weighing 500g or more should be counted. As a result, 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.

Note
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).

3-4 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 live births).

The perinatal mortality rate is the number of stillbirths plus early neonatal deaths per 1000 total births.

3-5 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) ÷ (Number of live born + Number of stillborn infants) × 1000

For example, in a health care district with 5000 deliveries in a year, there were 4800 live births, 200 stillbirths and 50 early neonatal deaths (i.e. 250 perinatal deaths). Therefore, the annual perinatal mortality rate for that district is:

(200 + 50) ÷ (4800 + 200) × 1000 = 50

3-6 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.

3-7 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.

3-8 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 36/1000. This varies widely between different areas from 35/1000 in metropolitan areas, such as Cape Town, to over 50/1000 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 36/1000 which is similar to many other poor countries.

Note
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 about 30/1000.

3-9 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 districts where health authorities need to turn their attention.

3-10 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 these 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 primary 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.

3-11 What are the primary causes of perinatal death?

In South Africa the common identifiable primary causes of perinatal death are:

  1. Spontaneous preterm labour.
  2. Intrapartum hypoxia.
  3. Antepartum haemorrhage.
  4. Hypertensive disorders.
  5. Infections.
  6. Fetal abnormalities.
  7. Intrauterine growth restriction.
  8. Birth trauma.
  9. Maternal diseases.

A few perinatal deaths are due to less common conditions or problems not related to the pregnancy (e.g. motor car accidents or assault).

Note
Most of the data on stillbirths and perinatal deaths in South Africa is taken from the Fifth Perinatal Care Survey of South Africa which covers the years 2003 to 2006.

3-12 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. With better examination of the clinical details the percentage of unknown causes will fall.

3-13 What are the commonest primary causes of perinatal death in South Africa?

In South Africa (and many developing countries) the three most common primary causes of perinatal deaths are:

  1. Unexplained intrauterine death.
  2. Spontaneous preterm labour.
  3. Intrapartum hypoxia.

Unexplained intrauterine deaths, spontaneous preterm labour and intrapartum hypoxia are the commonest primary causes of perinatal death.

3-14 Why is it important 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.

3-15 What causes spontaneous preterm labour?

Preterm labour (labour before 37 weeks gestation), which has not been induced artificially, may be caused by:

  1. Chorioamnionitis (often asymptomatic).
  2. Preterm prelabour rupture of the membranes (with or without obvious chorioamnionitis).
  3. Cervical incompetence.

Mothers who are HIV positive are also at higher risk of preterm labour. Often no obvious underlying cause can be found.

3-16 What are the important causes of intrapartum hypoxia?

  1. Labour related, especially prolonged labour, cephalopelvic disproportion and a hypertonic uterus.
  2. 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.

3-17 What are the likely causes of many unexplained deaths?

  1. Intrauterine growth restriction.
  2. Syphilis.

Almost all the unexplained stillbirths are macerated at delivery indicating that they probably died before the onset of labour. Careful measurement of the symphysis-fundus height during pregnancy, maternal awareness of the importance of reduced fetal movements, and routine screening for syphilis at booking for antenatal care will hopefully prevent many of these deaths.

Stillbirths

3-18 What is a stillbirth?

A stillbirth (SB), or stillborn infant, is an infant which is potentially viable but is born dead. Potentially viable means that the infant would have had a reasonable chance of surviving if it was born alive. Born dead means that the infant shows no sign of life at delivery.

A stillbirth is an infant that is born dead.

Note
Stillbirths are sometimes referred to as intra-uterine deaths or fetal deaths.

3-19 Which infants are potentially viable?

This depends on the level of maternal and neonatal care available. In many small hospitals, infants weighing less than 1000g, or with a gestational age of less than 28 weeks, are not regarded as potentially viable. However, in metropolitan areas, infants weighing less than 1000 g often survive. With good care (level 1 or 2 care) many of these small infants can also survive in a district hospital. Therefore, in South Africa all infants weighing 500 g or more at birth should be regarded as potentially viable and must be counted.

Note
In some industrialized countries, infants born as early as 23 weeks may survive with intensive care.

In South Africa all infants weighing 500 g or more must be counted as they are regarded as potentially viable.

The legal definition of stillbirth in South Africa is an infant born dead after ‘6 months of intra-uterine life’ (i.e. 28 weeks since the start of the last period or 26 weeks since conception). Infants that are born dead before this time are legally regarded as miscarriages. If the gestational age is not known, a weight of 1000 g is used to legally define a stillbirth.

Only legally defined stillborn infants require a stillbirth certificate (i.e. infants weighing 1000 g or more, or with a gestational age of 28 weeks or more). In practice, infants born dead and weighing less than 1000 g do not need a death certificate. This can be issued by a doctor, nurse or midwife. Stillborn infants requiring a notification of death certificate have to be buried or cremated. Smaller infants can be incinerated if the parents agree.

Stillborn infants weighing 1000 g or more require a stillbirth certificate and have to be buried or cremated.

However, for the collection of information on perinatal mortality for statistical purposes, the international rather than the legal definition of stillbirth should be used.

A stillbirth certificate can be issued by either a midwife or a doctor.

3-21 What is the international definition of stillbirth?

Any infant who is born dead and weighs 500 g or more is internationally defined as a stillbirth. Therefore, when the stillbirth rate is calculated, all infants who are born dead and weigh 500 g or more must be included. The normal fetus weighs 500g at about 22 weeks of gestation.

When the international definition of stillbirth (500 g or more) is used to collect perinatal data, the legal definition (1000 g or more) is still used to decide who needs a stillbirth certificate and requires to be buried or cremated. This saves the cost of burial or cremation for many parents.

For the purpose of collecting perinatal statistics, all infants weighing 500 g or more at delivery should be counted as stillbirths or liveborn infants.

3-22 What is a miscarriage?

When collecting perinatal data, infants born dead who weigh less than 500 g should be regarded as miscarriages. The word miscarriage is preferred to abortion as the latter suggests that the delivery may have been criminally induced.

A miscarriage is defined as an infant weighing less than 500 g at birth and showing no signs of life at delivery.

All infants showing signs of life at birth are called live born infants.

Note
The definition for live born infants under 500 g is difficult if the international definition of stillbirth is used. If these infants only gasp a few times and die within minutes of delivery, they are usually regarded as miscarriages. However, live born infants under 500 g who breathe well and survive for a few hours, especially if they are moved from the labour ward to the nursery, are usually counted as live born infants.

3-23 What should be done when a stillborn infant weighing between 500 and 999 g is delivered?

In South Africa:

  1. The parents may regard the pregnancy as ending with a miscarriage.
  2. There is no legal need to issue a stillbirth certificate.
  3. The body can be incinerated by the hospital if the parent’s agree. However, if the parents want to bury the infant, it is often easier if a stillbirth certificate is issued by a midwife or doctor, even though this is not a legal requirement.
  4. The infants should still be counted as a stillbirth for statistical purposes and entered in the birth register.

3-24 What is the stillbirth rate?

The stillbirth rate is the number of stillborn infants per 1000 total deliveries (i.e. live born and stillborn).

The stillbirth rate is calculated as:

Total number of stillborn infants ÷ Total number of infants delivered × 1000

3-25 What is the stillbirth rate in industrialised countries?

In an industrialised country the stillbirth rate is about 5 per 1000 for infant weighing 500 g or more.

3-26 What is the stillbirth rate in poor countries?

In poor countries the stillbirth rate is usually about 45 per 1000 for infants of 500 g or more.

Therefore the stillbirth rate in poor communities is much higher than that in high income communities.

3-27 What is the stillbirth rate in South Africa?

The information is not available to give an accurate stillbirth rate for the whole of South Africa. However, it is estimated that the stillbirth rate for South Africa, for infants weighing 500 g or more, is about 24 per 1000. The rate varies from about 23 in poor rural areas to about 25 in cities.

The stillbirth rate is about a third less if only infants of 1000 g or more are included.

Note
For infants of 1000 g or more the stillbirth rate is about 3.5/1000 for industrialised countries and about 35/1000 in poor countries. In South Africa the estimated stillbirth rate for infants of 1000 g or more is 19/1000.

3-28 What determines the stillbirth rate?

The stillbirth rate is determined by both:

  1. The health of women during pregnancy.
  2. The quality and availability of antenatal and labour care.

The number of induced midtrimester abortions will also influence the stillbirth rate.

3-29 Why is it important to know the stillbirth rate?

Because the stillbirth rate gives a measure of the health of pregnant women and the standard of care they receive during pregnancy and labour. Therefore, a high stillbirth rate suggests a poor level of health or poor antenatal and labour care or both. The stillbirth rate is one of the best measures of the health of pregnant women. The stillbirth rate can be compared between different regions or in one region between different periods of time. The stillbirth rate helps to identify communities in particular need of better health care.

The stillbirth rate is an indicator of maternal health and general obstetric care.

3-30 How can stillbirths be divided into groups?

Often stillborn infants are divided into two different groups as this helps identify the cause of a stillbirth and ways of preventing the stillbirth:

  1. Stillbirth that occur before the onset of labour.
  2. Stillbirths that occur during labour. Death may happen before or after arrival at a hospital or clinic.

Stillbirth before labour may indicate problems in the antenatal care of women. In contrast, infants that die during labour (intrapartum stillbirths) after the mother has been admitted to a clinic or hospital can often be avoided with good monitoring during labour. Deaths during labour before the mother arrives at a hospital or clinic may be due to a delay in seeking help, often as the result of inadequate transport. Infants that die before labour are often macerated.

3-31 What is a macerated stillbirth?

The signs of maceration are discoloration and peeling of the skin leaving areas of raw tissue. The skull is usually soft, as the brain has become soft. The umbilical cord is usually stained a dark red or black. The amniotic fluid is usually darkly stained. Maceration is the result of the infant being dead for at least 12 hours. Most macerated infants have been dead for many days or even weeks. Macerated stillborn infants are assumed to have died before the onset of labour. Fresh stillbirths show no sign of maceration and have usually died during labour or shortly before the onset of labour.

Therefore the presence or absence of maceration helps to decide when the infant (fetus) died. Fresh stillbirths usually reflect the quality of intrapartum care (care in labour) while macerated stillbirths reflect the quality of antenatal care (care during pregnancy).

Macerated stillbirths have usually died before the onset of labour while fresh stillbirths have usually died during labour.

3-32 What are the primary causes of stillbirth?

The primary causes of stillbirth are very similar to the primary causes of perinatal death:

  1. Hypertensive disorders.
  2. Antepartum haemorrhage.
  3. Intrapartum hypoxia.
  4. Infections.
  5. Fetal abnormalities.
  6. Intrauterine growth restriction.
  7. Birth trauma.
  8. Maternal diseases.

In many stillborn infants the primary cause of death is not known, especially if the infant is macerated. In South Africa the primary cause of death is unexplained in 38% of stillbirths.

Note
A final (pathological) cause of death is usually only given for early neonatal deaths and not for stillbirths. The final cause of death in most stillbirths is fetal hypoxia, fetal undernutrition, infection or a major congenital abnormality. Very little can be done to address the final cause of stillbirth. Therefore every effort must be made to avoid or treat the primary cause.

3-33 Is preterm labour a cause of stillbirth?

Although preterm labour is sometimes listed as a cause of stillbirth, this must be uncommon as preterm labour alone should not cause an intrauterine death. However, many of the reason for preterm labour can kill the fetus, e.g. antepartum haemorrhage, infection and congenital abnormality.

Neonatal mortality

3-34 What is a liveborn infant?

A live born infant is defined as an infant that is potentially viable (able to survive) and shows any sign of life at birth (i.e. breathes or moves). In practice, only infants weighing 500?g or more, are included as live born infants. Therefore every effort must be made to include all infants born alive and weighing 500 g or more in the definition of a live born infant in South Africa.

A liveborn infant is an infant that weighs 500 g or more and shows signs of life at delivery.

Note
Live born infants below 500 g (or 22 weeks gestation) at birth who only live for a few minutes are usually regarded as miscarriages and are not issued with a notification of neonatal death certificate. Infants below 500 g at birth are usually regarded as live births rather than miscarriages only if they live for a number of hours after delivery. They should be issued with a notification of neonatal death certificate. Very uncommonly, even infants weighing less than 500 g can survive.

3-35 What is a neonate?

A neonate (or newborn infant) is a live born infant aged between birth and 28 completed days after delivery. Therefore, a paediatrician who specialises in the care of infants in the first month of life is called a neonatologist.

3-36 What is neonatal mortality?

This is the number of live born infants who die in the first 28 days of life. They are known as neonatal deaths. All live born infants who die in the first 28 days of life must be issued with a notification of death certificate by a doctor (often, but incorrectly called a death certificate). Nurses and midwives may not sign a notification of death certificate. Neonatal mortality can be divided into early and late neonatal mortality.

Every liveborn infant that dies in the first 28 days of life must have a notification of death certificate signed by a doctor.

3-37 What is early neonatal mortality?

An early neonatal death is a death which occurs in the first week of life. Therefore, early neonatal mortality is the number of infants who are born alive but die in the first 7 completed days of life (i.e. the first week after birth). Early neonatal deaths and stillbirths are added to give the perinatal mortality.

Early neonatal mortality is the number of liveborn infants that die in the first week of life.

Note
It is very important to include all infants who die the first week after they have already been discharged from the hospital or clinic where they were born. Otherwise many early neonatal deaths, especially those due to infection, are missed.

3-38 What is late neonatal mortality?

The late neonatal mortality is the number of live born infants who die after 7 days but before 29 days of life(i.e. during the second, third and forth week of life). Neonatal mortality, therefore, consists of both early and late neonatal deaths.

3-39 What is the early neonatal mortality rate?

The early neonatal mortality rate is the number of live born infants that die in the first week of life per 1000 live born deliveries. Only live born infants are considered when calculating the early neonatal mortality rate.

The early neonatal mortality rate is calculated as:

The number of early neonatal deaths ÷ The number of live born infants × 1000

Note that early neonatal death rate is given per 1000 liveborn infants. This is different to the perinatal mortality rate and stillbirth rate which are expressed per 1000 total births (i.e. stillbirths plus live births).

The early neonatal mortality rate forms the greater part of the neonatal mortality rate (2/3) as most infants who die in the first month of life die in the first week. Most infants who die in the first week of life die on the first day.

The early neonatal mortality rate is the number of liveborn infants who die in the first week per 1000 liveborn infants.

Note
The late neonatal mortality rate is the number of infants who die from 8 to 28 days after birth per 1000 live born infants. An infant that dies on day 7 is an early neonatal death while an infant who dies on day 8 is a late neonatal death. The early plus the late neonatal mortality rate gives the neonatal mortality rate. The late neonatal mortality rate is not often calculated as many of these infants are no longer cared for by the neonatal services when they die. As a result the calculated late neonatal mortality rate is often incorrectly low.

3-40 What is the importance of the early neonatal mortality rate?

The early neonatal mortality rate is one of the most important measures of perinatal care. It is mainly a marker of the standard of health care given to the mother during labour and to the infant during the first week of life. The standard of care to the infant is the major factor determining the early neonatal death rate. A high early neonatal death rate strongly suggests a poor standard of newborn care.

The early neonatal mortality rate is an indicator of care of the mother during labour and care of the infant during the first week of life.

3-41 What is the early neonatal mortality rate in industrialised countries?

About 5 per 1000 live births for infants weighing 500 g or more. This is very similar to the stillbirth rate in industrialised countries.

3-42 What is the early neonatal mortality rate in poor countries?

About 25/1000 live births for infants weighing 500 g or more, i.e. about half the stillbirth rate.

###3-43 What is the early neonatal mortality rate in South Africa?

It is about 12/1000 for infants weighing 500?g or more, i. e. half the stillbirth rate.

Note
The early neonatal death rate is about 8.5/1000 for infants of 1000 g or more in South Africa, i.e. about two thirds the rate for infants of 500 g or more . The early neonatal death rate for infants of 1000 g or more is about 35/1000 in industrialised countries and 15/1000 or more in poor countries.

3-44 How are the causes of early neonatal mortality classified?

  1. As with stillbirth, it is important to identify the primary (obstetric) causes of early neonatal mortality. This is the problem or maternal illness during pregnancy, labour or delivery which resulted in the infant dying.
  2. However, the final cause of early neonatal deaths must also be looked for. This is the clinical problem at the time of the infant’s death.

The primary cause explains why the infant died while the final cause explains how the infant died. Therefore, both the primary and final cause of death should be established in each early neonatal death. For example, the primary cause of death may have been spontaneous preterm labour while the final cause of death was hyaline membrane disease.

Note
Unlike early neonatal deaths, the final causes of stillbirth are usually not sought as very little can be done to address the final cause of stillbirth (fetal hypoxia or septic shock).

3-45 What are the primary causes of early neonatal mortality?

The primary causes of early neonatal death are the underlying clinical (obstetrical) problem during pregnancy or delivery which eventually in the infant’s death. The primary causes of stillbirth and early neonatal death are the same with the exception that preterm labour is a very important primary cause of early neonatal death but not stillbirth. Knowing the primary causes should lead to a preventative programme.

3-46 What are the final causes of early neonatal death?

The final causes are the problems which actually killed the infant. The commonest final causes of early neonatal death are:

  1. Immaturity related (born too soon).
  2. Perinatal hypoxia (too little oxygen to the fetus or newborn infant).
  3. Infection (both fetal and neonatal).
  4. Congenital abnormalities.

Knowing the final causes helps identify the medical interventions needed to prevent the death. Less common causes include birth trauma, haemorrhagic disease of the newborn, Rhesus disease and cot death.

While most neonatal deaths have a primary cause during pregnancy and labour, some neo­natal deaths are due to events which occur after a normal pregnancy and delivery, e.g. infection acquired in the nursery or haemorrhagic disease of the newborn. With these conditions there is often no primary cause.

3-47 What are the final causes of early neonatal death in South Africa?

Most early neonatal deaths in South Africa and other poor countries are due to:

  1. Immaturity (born too soon).
  2. Fetal hypoxia (too little oxygen to the fetus).
  3. Infection (both fetal and neonatal).

In industrialised countries, immaturity, infection and congenital abnormalities are more common than fetal hypoxia.

The commonest final causes of early neonatal death are immaturity, fetal hypoxia and infection.

3-48 Are the final causes of early neonatal death always known?

No. Unfortunately the cause of early neonatal death is not always known. However, with a careful obstetric and perinatal history and careful examination of the infant, a cause can usually be found. The gross and histological examination of the placenta is very useful when there is no obvious cause of death. Placental signs of poor maternal blood flow to the placenta (causing fetal hypoxia) and infection (especially chorioamnionitis and syphilis) are very useful. A full post mortem examination by a pathologist is indicated if no obvious cause of death can be found. With more detailed maternal history and careful examination of the newborn infant and placenta, the number of unexplained deaths will decrease.

Careful clinical examination of the infant and placenta helps identify the final cause of early neonatal death.

3-49 What are the primary causes of fetal hypoxia resulting in early neonatal death?

Fetal hypoxia means that the fetus does not receive enough oxygen. The common primary causes of fetal hypoxia resulting in early neonatal death are:

  1. Antepartum haemorrhage, especially placental abruption.
  2. Hypertensive disorders.
  3. Intrapartum hypoxia, especially prolonged or obstructed labour or a prolapsed umbilical cord.
  4. Intra-uterine growth restriction (severe fetal undernutrition).
Note
As hypoxia may also occur after delivery if neonatal resuscitation is inadequate, some clinicians prefer to speak of perinatal hypoxia rather than just fetal hypoxia. It is best to avoid the confusing word ‘asphyxia’.

3-50 How do these primary causes of early neonatal death result in fetal hypoxia?

  1. With placental abruption part of the placenta separates from the uterine wall. In addition the uterus goes into spasm. Both reduce maternal blood supply to the placenta.
  2. Prolonged or obstructed labour results in excessive uterine contractions with little relaxation.
  3. A prolapsed cord is compressed and the umbilical arteries often go into spasm. Both reduce the blood flow between the placenta and fetus.
  4. In the hypertensive disorders the maternal blood vessels to the placenta (spiral arteries) are partially or completely obstructed reducing maternal blood flow to the placenta. Similarly, with intrauterine growth restriction (IUGR), there is often reduced maternal blood flow to the fetus. This causes a lack of both oxygen and nutrition. As a result, these fetuses grow slowly and are wasted (fetal weight loss due to starvation). These infants are often underweight for their gestational age at birth (UGA).

Sometimes there is no obvious cause of the fetal hypoxia.

These primary causes may also result in a stillbirth.

3-51 What fetal infections cause early neonatal death?

The most important cause is congenital syphilis because it is common in many poor communities and yet can be easily diagnosed and treated. One of the most effective methods of reducing both the stillbirth and early neonatal mortality rates is to introduce early screening for syphilis in pregnancy and a reliable system of treating maternal syphilis.

Severe chorioamnionitis and malaria may also cause stillbirth or early neonatal death. In some countries malaria is a common cause of perinatal death.

Note
Chorioamnionitis causes placenta oedema while malaria parasites obstruct the spiral arteries.

3-52 What serious congenital abnormalities may cause early neonatal death?

Usually chromosomal abnormalities (e.g. trisomy 18) or major brain or heart abnormalities.

The ratio of stillbirths to early neonatal deaths

3-53 What is the value of comparing the stillbirth and early neonatal mortality rates?

The stillbirth to early neonatal death ratio gives an idea of the standard of health care in a community. When ever possible, all deaths of 500 g or more should be included.

In an affluent community with good perinatal care the stillbirth and early neonatal mortality rates are similar giving a stillbirth to early neonatal death (SB:ENND) ratio of about 1. However, in a poor community, with inadequate perinatal care, the stillbirth rate is usually at least double the early neonatal death rate, i.e. the SB:ENND ratio is 2 or more. In South Africa the ratio is about 2 (i.e. SB rate is 24/1000, and ENND rate is 12/1000).

Usually, the higher the ratio, the poorer is the perinatal care. A low rate usually indicates good perinatal care.

Examining the individual stillbirth and early neonatal deaths rates is more important that simply looking at the SB:ENND ratio.

Note
If the standard of neonatal care is very poor, the neonatal mortality rate may rise markedly and the stillbirth and early neonatal mortality rates may again become similar, giving a SB:ENND ratio of about 1. In addition, very good neonatal care may result in a high SB:ENND ratio. Therefore, the SB:ENND ratio must not be looked at in isolation.

Perinatal care index

3-54 What is the perinatal care index?

The perinatal care index is the ratio of the perinatal mortality rate to the low birth weight rate. The perinatal care index is calculated as follows:

Perinatal rate ÷ Low birth weight rate

In addition, the early neonatal care index can be calculated by dividing the early neonatal mortality rate by the low birth weight rate.

3-55 What is the importance of knowing the perinatal care index?

As with the stillbirth to early neonatal death ratio, the perinatal care index is a useful method of comparing the standard of health care between different areas.

The perinatal mortality rate reflects the standard of perinatal care while the low birth weight rate reflects the socioeconomic status of the community and is little influenced by health care. Therefore, an area with many low birth weight infants (i.e. a poor community) usually has a high perinatal mortality rate (poor care). In contrast, communities with few low birth weight infants (i.e. privileged communities) usually have a low perinatal mortality rate (good care).

If a community with few low birth weight infants has a high rate of perinatal deaths (i.e. a high perinatal care index), then the level of perinatal care is probably particularly poor. Even in poor communities, the perinatal care index can be low if perinatal care is good.

The higher the perinatal care index the poorer is the perinatal care.

Similarly the early neonatal care index can be used to compare the quality of early neonatal care to the low birth weight rate.

Note
Correcting for the LBW rate controls for environmental factors and, thereby, makes the comparison of the perinatal mortality rate more valid between different site.

3-56 What is the perinatal care index in South Africa?

In South Africa, the perinatal mortality rate is about 36/1000 (for infants weighing 500 g or more) and the low birth weight rate about 15%. Therefore, the average neonatal care index is about 2.4 (i.e. 36/15). The perinatal care index varies widely from one area to another.

With the improvement of perinatal care, especially antenatal care and care of newborn infants, the perinatal care index will fall.

Note
South Africa has an early neonatal care index of 0.8 (12/15) for infants of 500 g or more.

Case study 1

At regular perinatal mortality meetings during the year in a regional hospital, 200 stillbirths and 80 early neonatal deaths were discussed. Twenty thousand infants were delivered alive or dead in the same year.

1. What is a perinatal death?

Either a stillbirth or an early neonatal death.

2. What is the lowest cut off weight for perinatal deaths?

It is best to use 500 g. However, some countries still use 1000 g. In South Africa all perinatal deaths of 500 g or above should be included as infants of 500 g or more are potential survivors with good care.

3. What is the perinatal mortality rate in this hospital?

All the stillbirths plus neonatal deaths expressed as a proportion of the 20 000 total births. By convention, perinatal deaths are given per 1000 births. Therefore, the perinatal mortality is 200 + 80 = 280 divided by 20 000 and then multiplied by 1000. This gives a perinatal mortality rate of 14/1000 for this hospital.

4. What is the perinatal mortality rate of poor and industrial countries?

In poor countries the perinatal mortality rate is usually 70/1000 or more while in industrial countries it is usually about 10. Therefore, a perinatal mortality rate of 14/1000 is very good and suggest a developed country or a privileged community in a poor country. It is essential to find out whether 500 g or 1000 g is being used as the cut off weight before comparing the perinatal mortality rate between two countries.

5. What is the perinatal mortality rate in South Africa?

The exact perinatal mortality rate is not known. However the estimated perinatal mortality rate is 36/1000. This is slightly less than that expected in poor countries but still six times that in industrialised countries.

6. Why is it important to know the perinatal mortality rate?

Because the perinatal mortality rate is a good measure of the standard of health in the community. Not surprisingly, the perinatal mortality rate also reflects the socioeconomic status of the community, as the standard of health is often low in poor communities and good in wealthy communities.

Case study 2

At a perinatal mortality meeting the most likely primary causes of all the stillbirths and early neonatal deaths are debated and then recorded. The commonest primary cause of death was spontaneous preterm labour.

1. What is a primary cause of perinatal death?

This is the underlying obstetric problem during pregnancy or delivery which resulted in the stillbirth or early neonatal death. The primary causes of stillbirths and early neonatal deaths are very similar and, therefore, are often considered together.

2. Is spontaneous preterm labour a common primary cause of perinatal death in South Africa?

Yes. Spontaneous preterm labour is a common primary cause of perinatal death in most poor and industrialised countries. In South Africa the commonest primary causes of perinatal death are spontaneous preterm labour, ante­partum haemorrhage and intrapartum hypoxia.

3. Why is it important to look for the primary cause of perinatal death?

Because they can often be prevented. Management protocols during pregnancy, labour and delivery must aim at avoiding perinatal deaths.

4. What are the main causes of spontaneous preterm labour?

Chorioamnionitis, preterm rupture of the membranes and cervical incompetence. Preterm rupture of the membranes is often caused by chorioamnionitis. Unfortunately, many cases of spontaneous preterm labour are still unexplained.

5. Which type of antenatal haemorrhage is a common cause of perinatal death?

Placental abruption. Placenta praevia is a far less common cause of perinatal death.

6. What is the commonest cause of intrapartum hypoxia?

Labour, especially if it is prolonged, if cephalopelvic disproportion is present or if the uterus is hypertonic. Very often all three factors occur together. Less commonly intrapartum hypoxia is due to a prolapsed cord.

Case study 3

At a perinatal mortality meeting in a primary care clinic, there is disagreement about the definition of a stillbirth. Of the 250 deliveries during the past month, five infants were born dead and all weighed between 500 and 1000 g. Most of the staff believe that all infants born dead and weighing less than 1000 g should be called miscarriages and need not be issued with a death certificate. Neither do they have to be cremated or buried.

1. What is the international definition of a stillbirth?

Any infant that is born dead and weighs 500 g or more is a stillbirth. Every effort must be made to use this definition in South Africa when perinatal death data are collected. In their mortality report, an infant which is born dead and weighs less than 500 g should be called a miscarriage. It is better not to call a miscarriage an abortion.

2. Should these five stillbirths be issued with stillbirth certificates and must they be cremated or buried?

No. In South Africa miscarriages or stillborn infants weighing less than 1000 g do not need a stillbirth certificate as they are legally miscarriages and not stillbirths. This is very confusing as the legal definition of a stillbirth and the international definition of a stillbirth are not the same. In the future, the legal definition of stillbirths in South Africa may be changed to agree with the international definition. However, at present we use the international definition for data collection and the South African legal definition for deciding who needs a stillbirth certificate and has to be cremated or buried.

3. What is the stillbirth rate at this perinatal mortality meeting?

Of the 250 deliveries there were five stillbirths. Therefore, the stillbirth rate is 5/250 x 1000 = 20/1000. Stillbirths are always expressed per 1000 total births (live births and stillbirths).

4. What is the stillbirth rate in industrialised and poor countries?

The stillbirth rate is about 5 industrialised countries and 45 in poor countries for infants weighing 500 g or more.

5. What is the stillbirth rate in South Africa?

It is estimated that the stillbirth rate in South Africa is 24/1000 for infants weighing 500 g or more at birth.

6. What is a macerated stillbirth?

A stillborn infant with discoloured, peeling skin, a dark red or black umbilical cord, a soft skull and darkly stained amniotic fluid. Maceration suggests that the infant has been dead for days or weeks and probably died before the onset of labour.

7. What are the primary causes of stillbirth?

These are the same as the primary causes of all perinatal deaths (i.e. both stillbirths and early neonatal deaths) and include intrapartum hypoxia, antepartum haemorrhage, hypertensive disorders and infection. Note that preterm labour is not a cause of stillbirth. In many stillbirths there is no obvious cause found.

Case study 4

Over six months 3000 live born infants are delivered in a busy hospital. Of these, 24 die during the first week of life. During the same period there are 20 stillbirths and 210 infants who weigh less than 2500 g at delivery.

1. What is the early neonatal death rate?

Eighteen infants died during the first 7 days. Therefore, there were 7 early neonatal deaths out of 3000 live born infants. As the early neonatal death rate is always expressed per 1000 live born deliveries, the early neonatal death rate in this hospital is:

24 ÷ 3000 × 1000 = 8/1000

2. What is the estimated early neonatal death rate in South Africa?

It is about 12/1000 live births. This is much higher than about 5/1000 in industrialised countries but a lot lower than and not much less than about 25/1000 in most poor countries.

3. How are the causes of early neonatal death classified?

Causes of early neonatal mortality are divided into primary causes and final causes. As with stillbirths, the primary cause is the obstetric problem or illness during pregnancy, labour or labour which led to the death. The final cause is the clinical problem at the time of the infant’s death.

4. What are the four common final causes of early neonatal death?

Immaturity, perinatal hypoxia, infection or congenital abnormalities. The first three are the commonest final causes of early neonatal death in South Africa.

5. What are the common primary causes of fetal hypoxia?

Placental abruption, hypertensive disorders, intrapartum hypoxia and intra-uterine growth restriction.

6. What infection is a common primary cause of early neonatal death in South Africa?

Syphilis. A less common cause is severe chorioamnionitis.

7. What is the ration of stillbirths to early neonatal deaths in this hospital?

There were 20 stillbirths and 24 early neonatal deaths giving a stillbirth to early neonatal death ratio of 20/24, i.e. 0.8. This is typical of industrialised countries. In most poor communities there are more stillbirths than neonatal deaths giving a ration of 2 or more.