Maternal collapse is rare in Australia and New Zealand, and maternal death even rarer. Not all maternal deaths are preceded by an identifiable collapse, and not all maternal collapses result in death. Maternal collapse occurs any time during pregnancy, up to 42 days following delivery and is an acute event involving cardiorespiratory systems and/or brain, resulting in impaired consciousness or death.¹

Maternal deaths are generally quantified as a maternal mortality ratio (MMR), expressed as the number of maternal deaths per 100,000 women giving birth. It includes deaths that occur due to complications of the pregnancy (direct deaths), and those resulting from worsening of other disease processes due to the pregnancy (indirect deaths). Deaths that occur from causes completely unrelated to pregnancy or birth are termed incidental deaths, and are not included in calculation of the MMR.

The MMR in Australia in the period 2008–12 was 7.1,² and in New Zealand, for the period 2011–13, was 16.8.³ While these numbers are thankfully low, the numbers of women who will collapse and require resuscitative care will clearly be higher. Most obstetricians working in Australia and New Zealand will not be directly involved in a maternal death, but many of us will be involved in a maternal resuscitation due to either an arrest or a non-arrest collapse. This is a ‘high stakes’ situation, where the life of both a young woman and her unborn child, or of a brand-new mother, may depend on our ability to remain calm and focused, to remember the modifications required to basic and advanced life support, and to consider all differentials and manage appropriately.

The leading causes of direct maternal death in Australia and New Zealand include thromboembolic disease, obstetric haemorrhage, hypertensive disease, amniotic fluid embolus and sepsis. Indirect deaths are most often attributable to cardiovascular disease and psychosocial causes; the latter includes suicide, drug and alcohol use, and domestic violence. It is vital to acknowledge and address the disparity for the Indigenous populations in our countries. In Australia, the MMR for Aboriginal and Torres Strait Islander women is twice that for non-Indigenous women. In New Zealand, the MMR for Māori and Pacific women is 2–3 times that for other women.

• Several other risk factors for maternal death are recognised. These include:
• Maternal age 35 and older
• Obesity
• Lower socioeconomic status
• Pre-existing mental health issues, substance use and domestic violence, all of which may be exacerbated by pregnancy and the puerperium
• Medical co-morbidities, particularly asthma, autoimmune diseases, inflammatory and atopic disorders, haematological disorders, essential hypertension, infections and musculoskeletal disorders

One of the important developments in improving identification of a pregnant or postnatal patient at risk of collapse during hospital admission has been the development of maternity-specific Early Warning Charts. These charts for regular observations consider the altered physiology of pregnancy, and provide clear guidelines for when observations fall outside the realm of expected or acceptable, thereby triggering an alert to the responsible obstetrician. These charts make recognition of a deteriorating maternity patient much easier, allowing timely medical intervention. All units responsible for the care of pregnant and postnatal patients should have such charts available and in use.

As for all cases of collapse, the initial resuscitation must follow the usual ABCs.

• Get help
• Airway
  – Ensure open by correct positioning of patient
• Breathing
  – If no respiratory effort, initiate basic life support (BLS)
  – Assess respiratory rate, check pulse oximetry
  – Use high flow oxygen
• Circulation
  – If no pulse, initiate BLS
  – Assess pulse, blood pressure, capillary return
  – Large-bore intravenous access, fluid resuscitation, take appropriate bloods
  – Proceed to advanced life support (ALS) as required.

In any patient collapse scenario, a primary and secondary survey both need to occur alongside the ongoing resuscitation. A few modifications of these surveys should be remembered for the pregnant and postpartum patient. Primary survey of the head, heart and chest proceeds as normal, with abdominal assessment including uterine size, evidence of fetal life, and determination of need for immediate delivery. Vaginal assessment is also added to the primary survey, with blood loss, trauma and stage of labour all being important. The secondary survey will include information gathering about the patient history and the circumstances surrounding the collapse, continued review of the examination findings including vital observations, initiation of appropriate investigation, and refining of the differential diagnosis with commencement of targeted therapy.

When faced with an acute maternal collapse, it is helpful to think of potential causes as falling into five categories, or the 5 Hs for simplicity:⁴
Head including eclampsia, stroke, epilepsy, vasovagal
Heart including myocardial infarction, arrhythmia, cardiomyopathy, thoracic aortic dissection
Hypoxia including pulmonary embolus, pulmonary oedema, anaphylaxis, asthma
Haemorrhage including abruption, uterine atony, genital tract trauma, uterine rupture, uterine inversion, ruptured aortic aneurysm
wHole body and Hazards amniotic fluid embolus, hypoglycaemia, trauma, anaesthetic complications, drug reactions (illicit or prescribed), sepsis

The likelihood of any one of these being causative will obviously depend somewhat on the timing of the collapse – early or late pregnancy, intrapartum, immediately postpartum, remotely postpartum.

Maternal cardiac arrest represents a small subset of women affected by maternal collapse. The incidence is approximately 1 in 30,000 ongoing pregnancies, with a high likelihood of death for both the mother and the fetus. The vast majority of us will never need to attend a maternal cardiac arrest, and doing so is uniquely stressful. For these reasons, it is important to have a framework in mind of how to deal with a maternal cardiac arrest, and to have practised the response to this situation.

Many changes of pregnancy may adversely affect attempts at resuscitation:

• The enlarged gravid uterus can cause aortocaval compression with the patient lying flat on her back, resulting in reduced return of blood to the heart and therefore reduced cardiac output.
• Pressure from the uterus will splint the diaphragm, the extent depending on gestation, with subsequent increased pressure required for successful ventilation.
• Increased breast tissue will reduce chest wall compliance and make ventilation more difficult.
• The fetal haemoglobin circulating in the fetus and placenta has a higher affinity for oxygen than adult haemoglobin, which is an adaptation designed to ensure optimal fetal oxygenation. In the setting of maternal resuscitation, however, this allows the fetus to ‘steal’ oxygen from the mother, meaning oxygen delivery to the maternal brain and myocardium is less efficient than in the non-pregnant patient.
• Increased intra-abdominal pressure, delayed gastric emptying and increased laxity of the lower oesophageal sphincter combine to increase the likelihood of reflux, and therefore aspiration, of stomach contents.
• Decreased chest wall compliance combined with increased mucous membrane swelling and fragility result in greater difficulty with intubation.
• Increased plasma volume of pregnancy is associated with a dilutional anaemia and subsequent reduced oxygen carrying capacity.
• A combination of changes in respiratory and metabolic functioning makes acidosis more likely to develop, and to do so more rapidly, meaning resuscitation needs to be even more efficient than usual.

For these reasons, there are modifications to routine resuscitation protocols that must be introduced when dealing with a cardiac arrest during pregnancy:

• Left lateral displacement of the uterus reduces the degree of aortocaval compression and thereby maximises cardiac output. This is most simply achieved manually, with one member of the team using a hand to push the uterus to the side while the mother is supine. Use of a wedge or other device to tilt the maternal pelvis may also be advocated, but can potentially also tilt the thorax and thereby reduce the efficiency and utility of cardiac compressions.
• Consideration of expediting delivery. If the patient is in labour and fully dilated, this may be most speedily achieved with forceps, but generally is most likely to require a perimortem caesarean section (PMCS). The benefit of PMCS to maternal survival is greatest if delivery is achieved within five minutes of arrest, so the procedure must commence by the four-minute point, and should be considered a possibility from the moment of the arrest. It is advisable that all units have a PMCS kit available both on the maternity ward and in the emergency department, or anywhere else that a maternal cardiac arrest is more likely to occur. This essentially only requires a scalpel and a clamp for the cord, the latter to prevent neonatal exsanguination if the baby is alive at birth. It is important to remember that the procedure is being performed for the benefit of the mother, not the fetus, but delivery may also improve the likelihood of neonatal survival. It is imperative that the neonatal team, or the person/team responsible for neonatal resuscitation, is called by the time the decision has been made to proceed to delivery.

One very simple way of ensuring a smoother response if a maternal collapse does occur on your unit is to have regular drills. Everyone working in the area, and everyone who may attend a maternal cardiac arrest call, should know where the emergency equipment is for your ward, including the PMCS kit, and should know how to apply and initiate the defibrillator. Good teamwork is vital in the event of any resuscitation, but even more so in an environment where arrest occurs infrequently and where stress levels will be even higher than in most other arrest scenarios. Many maternity units run regular drills for obstetric emergencies, and it is vital to include maternal collapse in these scenarios. Programs such as the PROMPT course are invaluable in educating staff members from all areas regarding the importance of teamwork, knowing the protocols, equipment and expectations for your unit, and the benefits of drills.

Maternal collapse is a sobering topic, with significant potential for complacency in our privileged setting of low maternal mortality. It is likely that as the obstetrician on the scene, we will be looked to as a leader in the event of maternal collapse or arrest, and it is vital that we are all educated about how to deal with this. We also have a duty to ensure every other obstetrician, midwife, paediatrician, nurse, anaesthetist, intensivist, orderly and anyone else who will respond to a maternity arrest call is aware that there are modifications required for BLS and ALS in the pregnant and immediately postnatal patient, and that teamwork is vital to achieving the best results. Increasingly, we also need to be aware of screening for risk factors that must occur antenatally, and the risk stratification and harm minimisation strategies that may be of use in some at-risk groups. As with everything in obstetrics though, one of the biggest challenges with maternal collapse is the unpredictability, and the need for constant vigilance.

1. Royal College of Obstericians and Gynaecologists. Maternal Collapse in Pregnancy and the Puerperium. Green-top Guideline No. 56. 2011.
2. Humphrey MD, Bonello MR, Chughtai A, et al. Maternal deaths in Australia 2008–2012 (AIHW Cat. No. PER 70; Maternal Deaths Series No. 5). Canberra: Australian Institute of Health and Welfare; 2015.
3. Perinatal and Maternal Mortality Review Committee. Ninth annual report of the Perinatal and Maternal Mortality Review Committee. Reporting mortality 2013. Wellington: PMMRC; 2015.
4. Winter C, Crofts J, Laxton C, et al (Eds) Sowter M, Weaver E, Beaves M. PROMPT PRactical Obstetric MultiProfessional Training Course Manual, Australian and New Zealand Edition. 2008.