Chapter 3 Maternal and perinatal mortality

David T Y Liu, Mentor: Charles Rodeck

CHAPTER CONTENTS

Maternal mortality 14

Cause of maternal mortality 14

Pulmonary thromboembolism and thrombosis 14

Haemorrhage 15

Hypertensive disorders 15

Amniotic fluid embolism 15

Sepsis 15

Genital trauma – uterine rupture 16

Anaesthesia 16

Perinatal mortality 16

Reports from the Confidential Enquiries into Maternal Deaths in the UK have appeared every 3 years since 1952 and are the first example of audit by the medical profession. The Department of Health document A First Class Service – Quality in the New NHS (1998) states that all health workers are required to participate in these enquiries. Information and case notes must be made available for enquiry assessors and reports completed within 9 months of the death. The 1994–1996 triennia audit emphasised awareness of social and public health issues. These issues include advice for seatbelt usage, identification and coordinated care for psychiatric disorders especially postnatal depression, impact of social sequestration from access to help and contribution from domestic violence.

These enquiries have led to substantial improvement in care and safety for childbirth. The direct maternal death rate for the 1994–1996 triennium is 6.1 per 100 000 maternities (total of 12.2 per 100 000 maternities). Women older than 40 years, high parity, thromboembolism, pregnancy hypertension, amniotic fluid embolism, sepsis, haemorrhage and uterine rupture remain as salient but often avoidable causations. There is no room for complacency. In the 2000–2002 triennium the direct death rate is 3.5 per 100 000 maternities. In the past 6 years indirect causes have exceeded direct causes of maternal deaths, emphasising the need for coordinated multidisciplinary care when a woman has an existing psychiatric or medical condition. Inadequate contribution and support from experienced senior obstetricians, and inappropriate delegation and treatment emphasise the need for protocols, teamwork and drills to address emergencies. The continuing challenge is to achieve year on year improvement in the safety and satisfaction of childbirth, using evidence-based practice.

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MATERNAL MORTALITY

Maternal mortality is defined by the International Classification of Diseases, Injuries and Causes of Death – Ninth Revision (ICD9; World Health Organization (WHO) 1993) as ‘death of a woman while pregnant or within 42 days of termination of pregnancy from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes.’ This is further subdivided into the following in which maternities are defined as pregnancies which result in a live birth at any gestation or a stillbirth occurring at or after 24 completed weeks’ gestation. (Note statement for twin pregnancies.)

• Direct obstetric death results from obstetric complications of the pregnancy state.

• Indirect obstetric death is where existing or pregnancy precipitated medical disorders led to or is associated with maternal mortality, for example following diabetes mellitus, cardiac diseases, vascular aneurysm, epilepsy or suicides.

• Fortuitous obstetric death is when pregnancy is incidental to the causation, for example road traffic accident, murder or unrelated malignancies.

• Late obstetric death. The ICD10 revision (WHO 1993) introduced inclusion of direct and indirect deaths ‘occurring between 42 days and one year after abortion, miscarriage or delivery.’ The last two Confidential Enquires included late deaths in their figures.

Cause of maternal mortality

Only direct and indirect deaths are counted for the Confidential Enquiries. The denominator is registered live or stillbirths and not total pregnancies as exact numbers of pregnancies are not known. International comparison is not reliable as not all countries use the same inclusion criteria. The increase in the maternal mortality figures for the 1994–1996 triennium reflected alterations in the baseline with inclusion of extra cases. Salient causes of death relevant to the labour ward remained similar for 2000–2002 and included pulmonary thromboembolism, hypertensive diseases, amniotic fluid emboli, sepsis and uterine rupture. Deaths due to anaesthesia and haemorrhage increased.

Substandard care continues as a contributory factor (over 50%). Steps for improvement include:

• Awareness of your limitations. Seek advice when there is uncertainty or doubt.

• Ensure delegation is appropriate for the level of competency.

• Consultants or experienced seniors must attend to assist or supervise where complications are anticipated.

• Become familiar with protocols, evidence-based practice and drills for emergencies. A team approach with inclusion of relevant disciplines is essential for complex situations or emergencies.

• Where possible identify potential risk in the antenatal period (e.g. risk assessment charts).

The lowest mortality is in the second pregnancy while age more than 40 remains a risk factor. Socially isolated ethnic groups, for example new immigrants with communication difficulties, need particular attention. The 2000–2002 Enquiry included the socially disadvantaged, the obese (body mass index (BMI) 35 or more) substance misuse, domestic violence and limited antenatal care as risk factors for maternal deaths. Psychiatric disorders were the leading cause of indirect maternal mortality for 1997–1999 and remained so in the 2000–2002 triennium.

Pulmonary thromboembolism and thrombosis

In the UK the rate of pulmonary embolism is between 1 and 2.1 per 100 000 maternities and remains the major direct cause of maternal mortality. Most women survive if thromboembolism is treated. Failure to provide prophylaxis, to diagnose the condition or consider possibility of diagnosis continues to place mothers at risk. The following steps should be taken to reduce risk:

• Identify family or personal history of thrombosis. Screening for thrombophilia and antiphospholipid antibody, for example cardiolipin, Leiden factor V mutation and anti-lupus anticoagulant may be appropriate to plan prophylaxis. Antenatal classification into low, moderate or high risk is helpful for focusing attention.

• Women older that 35 years weighing over 80 kg (BMI 35 or more), and after having four babies require some form of prophylaxis. Consider prophylaxis after 4 days of bed rest when there is pre-eclampsia, dehydration and major medical illness or infection.

• In addition to stockings, heparin prophylaxis in adequate doses must be prescribed when there is a personal or family history of thrombosis, thrombophilia or when major surgery is being contemplated.

• When there is a suspicion or there are symptoms suggestive of venous thrombosis or pulmonary embolism perform a duplex ultrasound examination or ventilation–perfusion lung scan.

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• Neither unfractionated nor low molecular weight heparin cross the placenta. Where risk is high prescribe unfractionated heparin 7500 units every 12 hours or equivalent (e.g. Clexane 20 mg or 2000 units for moderate risk and 4000 units for high risk 2 hours before surgery). Appropriate doses must be prescribed.

• Continue prophylaxis for 5 days or until mobilised. Women with a history of thromboembolism need prophylaxis for 6 weeks.

• In contemporary practice all caesarean sections are covered by prophylaxis for thromboembolism.

Haemorrhage

Death due to severe haemorrhage has fallen to 5.5 per 1 000 000 maternities. Haemorrhage occurs in 1 in 1000 deliveries, and the management of this complication can be improved by:

• appropriate delegation for difficult caesarean sections such as placenta praevia, particularly when the placenta is sited anterior with a previous caesarean section scar

• frequent drills to familiarise staff with protocols for severe haemorrhage, including test communication with blood banks. Recruit help from haematologists and anaesthetists. Postpartum haemorrhage (loss of 500 ml or more of blood) occurs in 1% of deliveries. Correct estimation of blood loss and being aware of clotting defect is important

• early resort to hysterectomy if bleeding continues despite simple procedures

• transfer of care to a tertiary unit when risk of haemorrhage is considered to be high

• consider agreeing on a management plan for women who decline blood products.

Hypertensive disorders

The following are suggested to improve care:

• Educate medical staff and women about the significance of complications, need for prompt attention or delivery, and benefit of a team approach in a referral centre where senior expertise is available. Proteinuria and/or hypertension can present alone before the full clinical picture.

• Clear guidelines and protocols must be in place for management of pre-eclampsia and eclampsia.

• Mortality due to hypertension ranges between 9 and 12 per 1 000 000 maternities. Mothers younger than 25 years are at particular risk. The risk also increases with age (>35), severe obesity and a family history of pre-eclampsia.

• An average of 6 days separate normality at antenatal review and subsequent onset of hypertension. Ensure close liaison with general practitioners and community midwives as the complication can arise between antenatal visits.

• Monitor severity and progression of pre-eclampsia by full blood count, uric acid, electrolytes, and liver and renal function tests. Fluid overload with pulmonary oedema and acute respiratory distress syndrome (ARDS) is a frequent cause of death. Cerebral pathology, particularly infarction and haemorrhage, is also significant.

• Administer antihypertensive drugs early to prevent high systolic blood pressure – a risk for intracerebral haemorrhage.

Amniotic fluid embolism

Sudden collapse (hypotension and cardiac arrest), respiratory distress, and cyanosis followed rapidly by death is suggestive of this complication but lung autopsy showing presence of squames and hair is needed for confirmation. Prevention is difficult but note the following:

• Strong uterine contractions, fetal distress and severe haemorrhage due to coagulopathy are other clinical features. Avoid uterine over-stimulation and delay in resolving obstructed labour.

• Complications increase with age (over 35 years) and high parity. Although classically associated with polyhydramnios and induction of labour with oxytocics, other obstetric complications can contribute. It is not common in a totally straightforward pregnancy but amniotic fluid embolism can present before onset of labour.

• Early transfer for intensive care is important when complication presents.

Sepsis

Puerperal sepsis has increased in the UK and remains the fourth major cause of maternal mortality. This is associated with increased virulence in streptococcal infections. To reduce the risk:

• Note history of infection especially haemolytic streptococcal infections. Exclude infections in complications such as prolonged membrane rupture or presence of a cervical suture.

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• Investigate promptly any pyrexia. (Pyrexia may be absent especially in severe sepsis.) Check full blood count. Note presence of thrombocytopenia. Obtain blood culture. Recruit help from microbiologist for severe infection. Do not wait for culture results before instigating broad-spectrum antibiotics.

• Prescribe prophylactic antibiotics where indicated. This is routine for caesarean section in contemporary practice.

Genital trauma – uterine rupture

Death rate due to uterine rupture is between 1.3 and 2.3 per 1 000 000 maternities. For further details see Chapter 14 and note the following when there is a uterine scar:

• An experienced obstetrician must assess suitability for vaginal delivery. Exclude risk of disproportion and pelvic anatomical deformities.

• Conduct delivery in an equipped unit with full maternal and fetal surveillance. An experienced obstetrician must supervise care.

• Emphasise again care with oxytocic usage for induction of labour and recognition of signs and symptoms of uterine rupture (Chapters 15 and 17).

Anaesthesia

The rate of death due to anaesthesia has dropped to 0.5 per 1 000 000 maternities (it was about 1.4 per 1 000 000 between 1997 and 1999). Between 2000 and 2002 there were 6 instead of 3 deaths all due to general anaesthesia with inadequate supervision of junior anaesthetists. Good communication within a multidisciplinary team, availability of consultant advice and support, prompt appropriate decisions and ready access to intensive care units will continue to reduce the contribution from anaesthesia to maternal mortality. The labour ward is not suitable for high dependency care. The following should be noted:

• Adrenaline is the drug of choice for severe anaphylaxis.

• All medical personnel should be aware of resuscitation techniques and airway maintenance.

• Identify at risk mothers antenatally for assessment by consultant anaesthetist.

PERINATAL MORTALITY

Perinatal mortality is defined as a stillbirth from 24 weeks onwards or the death of a liveborn baby at any gestational age within 7 days of birth (early neonatal death). Death of one twin delivered after 24 weeks is considered a stillbirth. Some countries accept the range from 20 weeks’ gestation to 28 days after birth hence comparisons must take the definition into consideration. In England and Wales the perinatal mortality is about 9 per 1000. Factors associated with perinatal mortality include:

• congenital and inherited abnormalities

• perinatal mortality is increased after the third birth, in multiple pregnancies and when birth weight is low such as preterm births and fetal growth restriction

• perinatal mortality is increased when women have obstetric and medical complications.

Discuss mode of delivery with women and their partners. If vaginal delivery is appropriate close surveillance is mandatory. The process of labour can exert hypoxic stress. If there is much fetal compromise deliver by caesarean section.

More important than mortality is maternal and fetal morbidity, for which we have no detailed statistics.

References

Department of Health. A First Class Service – Quality in the New NHS. London: Department of Health, 1998.

World Health Organization. International Classification of Diseases, Injuries and Causes of Death – Ninth Revision. Geneva: WHO, 1993.

World Health Organization. International Classification of Diseases, Injuries and Causes of Death – Tenth Revision. Geneva: WHO, 1993.

Bibliography

CESDI. The Fetal and Infant Postmortem. Maternal and Child Health Consortium 2000. London: CESDI, 2000.

Department of Health. Why Mothers Die. In: Report on Confidential Enquiries into Maternal Deaths in the United Kingdom 1994–1996. London: TSO; 1998.

Duley L, Gulmezoglu AM, Henderson-Smart DJ. Anticonvulsants for women with pre-eclampsia. Cochrane Database of Systematic Reviews, 2. 2000:CD000025. Update in: Cochrane Database of Systematic Reviews 2003 (2):CD000025

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Drife J. Management of primary post partum haemorrhage. British Journal of Gynaecology. 1997;104:275-277.

Holme SE. Invasive group A streptococcal infections. New England Journal of Medicine. 1996;335:590-591.

Polkinghorne J. Review of the Guidance on the Research use of Fetuses and Fetal Material. London: HMSO, 1989.

Royal College of Obstetricians and Gynaecologists. Why Mothers Die 2000–2002. The sixth report of the Confidential Enquiries into Maternal and Child Health (CEMACH) in the United Kingdom. London: RCOG Press, 2005.

Royal College of Obstetricians and Gynaecologists. Report of a Working Party on Prophylaxis against Thrombo-embolism in Gynaecology and Obstetrics. London: RCOG Press, 1995.

Scottish Office Department of Health. Acute Services Review Report. Edinburgh: SODH, 1998.

The Welsh Office. Quality Care and Clinical Excellence. Cardiff: The Welsh Office, 1998.

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