This week is Blood pressure awareness week in the UK, a campaign to be aware of your own blood pressure and “Know your Numbers”. Midwives are well aware of the importance of regular blood pressure checks during pregnancy. In this article Professor Andrew Shennan, Professor of Obstetrics, King’s College, London and Anastasia Martin FY2, University Hospital Sussex, discuss pre-eclampsia, and the innovative efforts currently aimed at preventing deaths from the condition globally.
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Preventing global deaths from pre-eclampsia: new strategies
Pre-eclampsia is a major cause of maternal mortality worldwide accounting for over 150 deaths a day. Many more babies die. There is no cure, other than delivery of the baby and it is the commonest cause of indicated preterm birth, accounting for over 10% of all early births, but even a higher proportion of very early preterm births. Yet in high income settings there has been a remarkable success in reducing mortality. In the UK, less than 1 in a million women will die from pre-eclampsia (1), making it safer than age matched mortality in men. This has been achieved through universal health care provision, and good antenatal surveillance, principally by midwives. Women with pre-eclampsia can be closely monitored, admitted to hospital and timely birth instigated before a life-threatening crisis.
Mothers can be managed with anti-hypertensive medication and anti-convulsant prophylaxis. Babies can be born in units that cope with preterm infants. Timely birth, although resulting in prematurity, is the definitive treatment. It also prevents many fetal deaths. Adverse effects on baby outcomes can be improved through antenatal corticosteroid administration to reduce respiratory morbidity and magnesium sulphate to reduce neurodisability. In one recent trial of early onset pre-eclampsia, not a single baby died in 900 cases of mothers diagnosed from 34 weeks gestation born in the UK (2)
Most mortality from pre-eclampsia occurs in low and middle income settings. So, the challenge is to instigate appropriate surveillance and birth in low resourced settings. There is a severe lack of midwifery and front-line health care staff to ensure this. The hallmark sign of pre-eclampsia is hypertension, which often appears some weeks before the need to deliver. This therefore can be used to flag who requires surveillance and arrange transfer and preparation for birth. Unfortunately, in many parts of the world, basic blood pressure measuring equipment is lacking, or not functional. Also, only a subset of women with hypertension are at significant risk. More than 10% of women will be hypertensive at some point in their pregnancy, yet fewer than half of these develop pre-eclampsia. In addition, serious outcomes such as intra-uterine fetal death, eclampsia or abruptions occur in only around 1% of women. The necessary diagnostic tests to triage women with pre-eclampsia into those requiring birth is even more challenging in low resourced settings. Scanning equipment, or the skills to use the equipment, to dictate when the baby should be safely delivered are rarely available.
So, what are the solutions? The cost of BP equipment is low, and there has been efforts to produce such a device at low cost that is suited to a low-income setting (3). The CRADLE VSA (vital signs alert) has been developed, not only to be low cost, but accurate and simple to use, with an early warning system (traffic light) to allow untrained individuals to use it. It is also available in the UK (action-on-pre-eclamsia.org.uk). It has been successfully used in dozens of countries and has even been scaled up nationally in Sierra Leone. Here, its adoption was associated with significant reductions in maternal mortality in an urban setting, (4) and ongoing work is evaluating its national scale up. As it also detects shock, it has even reduced referrals for haemorrhage while reducing the need for hysterectomy suggesting it will reduce health resource use, even in these challenging settings (5). One key uncertainty is when should a woman be delivered with pre-eclampsia in these settings? A recent trial has completed (6) to look at the impact of routine birth after 34 weeks in Zambia and India, rather than waiting for a crisis to dictate delivery. As many more babies die in these settings, preterm birth maybe justified to prevent intrauterine fetal deaths.
However, it remains crucial to ensure intervention to deliver does not occur inappropriately. Recently in the UK, angiogenic markers (PLGF like tests) have been introduced nationally to help manage women with suspected pre-eclampsia. Their use is associated with improved outcomes (7). These tests are a relatively expensive laboratory test. However new developments mean it may be used as a finger prick point of care test at lower cost. If the test is normal, it precludes the need for many other investigations and it has been very cost effective in high income settings (8). The challenge is adopting this worldwide, but this could be a simple cost effective solution to managing pre-eclampsia in low resourced settings where the morbidity is greatest. It is important that new technologies are appropriately evaluated in the setting they are intended to be used in, and clinical trials in low resourced settings are required before widespread adoption.
Midwives remain the front line in reducing mortality from pre-eclampsia. They can be proud of the success in the UK. Our challenge is to translate this success elsewhere. It won’t be easy, but if you would like to know more see the following websites: apecint.org and cribs-i.org or follow us on twitter @OBSevidence
References:
- Shennan AH, Green M, Chappell LC. Maternal deaths in the UK: pre-eclampsia deaths are avoidable. Lancet. 2017 Feb 11;389(10069):582-584. doi: 10.1016/S0140-6736(17)30184-8. No abstract available.PMID:28195043
- Chappell LC, Brocklehurst P, Green ME, et al; PHOENIX Study Group.
Planned early delivery or expectant management for late preterm pre-eclampsia (PHOENIX): a randomised controlled trial. Lancet. 2019 Sep 28;394(10204):1181-1190. doi: 10.1016/S0140-6736(19)31963-4. Epub 2019 Aug 28. PMID:31472930 Select item 31403111
- Nathan HL, Vousden N, Lawley E, et al; Development and evaluation of a novel Vital Signs Alert device for use in pregnancy in low-resource settings. BMJ Innov. 2018 Oct;4(4):192-198. doi: 10.1136/bmjinnov-2017-000235. Epub 2018 Sep 19.PMID:30319784
- Vousden N, Lawley E, Nathan HL, et al; CRADLE Trial Collaborative Group. Effect of a novel vital sign device on maternal mortality and morbidity in low-resource settings: a pragmatic, stepped-wedge, cluster-randomised controlled trial.Lancet Glob Health. 2019 Mar;7(3):e347-e356. doi: 10.1016/S2214-109X(18)30526-6. PMID:30784635
- Giblin L, Vousden N, Nathan H, et al; Effect of the CRADLE vital signs alert device intervention on referrals for obstetric haemorrhage in low-middle income countries: a secondary analysis of a stepped- wedge cluster-randomised control trial. BMC Pregnancy Childbirth. 2021 Apr 21;21(1):317. doi: 10.1186/s12884-021-03796 -4.
- Beardmore-Gray A, Vousden N, Silverio SA, et al; Planned early delivery for late preterm pre-eclampsia in a low- and middle-income setting: a feasibility study. Reprod Health. 2021 Jun 2;18(1):110. doi: 10.1186/s12978-021-01159-y.PMID: 34078408
- Hurrell A, Beardmore-Gray A, Duhig K, et al; Placental growth factor in suspected preterm pre-eclampsia: a review of the evidence and practicalities of implementation [published online ahead of print, 2020 Jul 23]. BJOG. 2020;10.1111/1471-0528.16425. doi:10.1111/1471-0528.16425
- Duhig KE, Seed PT, Myers JE, et al; Placental growth factor testing for suspected pre- eclampsia: a cost-effectiveness analysis. BJOG. 2019;126(11):1390-1398. doi:10.1111/1471-0528.15855
Andrew H Shennan, Professor of Obstetrics, King’s College, London and Anastasia Martin, FY2, University Hospital, Sussex
September 2022