Pre-eclampsia

What is pre-eclampsia?

Pre-eclampsia is a condition where the blood flow between the mother and the baby is disrupted because the placenta does not receive enough blood from the mother’s body. It can occur in, or soon after, pregnancy, and although the exact causes are unclear, it is thought to be caused by problems with the placenta. According to Tommy’s pregnancy charity [1], pre-eclampsia affects up to 6% of pregnancies in the UK. Severe pre‑eclampsia develops in around 1–2% of UK pregnancies. 1 in 6 women who have had pre-eclampsia will have it again in a future pregnancy. Currently, there is no sure way to prevent pre-eclampsia. Some contributing factors, such as maintaining a healthy weight, can be controlled and some cannot (i.e., genetics, family history).

The National Health Service (NHS) website [2] lists the typical symptoms of pre-eclampsia, which include headaches, vision problems such as blurring or flashing before your eyes, feeling sick or vomiting, heartburn that is difficult to control with antacids, and swelling of the face, hands, or feet.

Pre-eclampsia Symptoms
Pre-eclampsia Symptoms

Pre-eclampsia is classified as one of four high blood pressure disorders that can occur during pregnancy. The symptoms of pre-eclampsia and how it differs from the other high blood pressure conditions are as follows [3]:

  • Gestational hypertension – characterised by high blood pressure but no excess protein in the urine or other signs of organ damage
  • Chronic hypertension – high blood pressure that was present before pregnancy or that occurs before 20 weeks of pregnancy
  • Chronic hypertension with superimposed pre-eclampsia – occurs in women who have been diagnosed with chronic high blood pressure before pregnancy, but then develop worsening high blood pressure and protein in the urine or other health complications during pregnancy

 Pre-eclampsia affects many different systems in the body and can present suddenly without warning, making it difficult to make a diagnosis. The risk factors of developing pre-eclampsia are listed below [4].

Pre-eclampsia risk factors
Pre-eclampsia risk factors

If you are diagnosed with pre-eclampsia, you will usually have additional ultrasound scans to monitor your baby’s growth and a series of blood tests to check if the disease has started to cause organ damage [5]. Because the placenta may not be working as well as it should be, the baby may not get all the nutrients and oxygen it needs, leading to foetal growth restriction. If the preeclampsia is severe, your baby may need to be delivered early. Premature birth may cause complications. About 60,000 infants a year are prematurely born in the UK, of which 85% are born between 32 and 37 weeks [6].  1 in 10 of all premature babies will have permanent disabilities such as cerebral palsy, epilepsy, deafness, and blindness. Infants who experienced poor growth in the uterus may later be at risk of diabetes, congestive heart failure, and high blood pressure [6][7].

About 80% of infants born before 27 weeks of gestation will develop respiratory distress syndrome (RDS). 1–5% of infants born at a gestational age of less than 25 or 26 weeks often require hearing aids. Visual impairment increases with decreased gestational age and decreasing birth weight [8].

Current therapies

The National Institute for Health and Care Excellence in the UK recommends expectant management until 37 weeks’ gestation for women with late preterm pre-eclampsia, with intervention only if the woman develops severe preeclampsia or associated complications [9].

Depending on the severity of pre-eclampsia, your doctor may prescribe medications to lower blood pressure and/or corticosteroids to help mature the baby’s lungs and improve the mother’s health. Doctors often recommend intravenous antiseizure medications, such as magnesium sulphate [10].

Low dose aspirin can also be prescribed and is considered the most robust therapy to reduce the risk of pre-eclampsia in high-risk groups of women [11]. However, some women are resistant to aspirin, in which case aspirin treatment is not effective. The reasons for aspirin resistance can vary depending on their genetic makeup, the type of aspirin taken for treatment, and if the aspirin is taken as prescribed [12]. This means that current therapeutic levels of aspirin in pregnancy will not help some women taking aspirin to prevent or delay preeclampsia. Also, resistance seems to be higher during pregnancy than postpartum [13].

Why pre-eclampsia research matters and possible future treatments

Pre-eclampsia is still called the “disease of theories” because its direct cause is still debated. Patients, providers, researchers, and funders remain critical to moving pre‑eclampsia research forward. Finding a cure for pre‑eclampsia goes beyond funding individual research studies – it involves advocating at a systematic level for the prioritisation of maternal and foetal health as a national (and international) issue that can and should be addressed.

The routine laboratory tests performed to check for organ damage in women with pre‑eclampsia are frequently normal and do not indicate whether pre-eclampsia exists, nor do they predict whether it will progress rapidly. Therefore, it can be difficult for doctors and midwives to know which women can be safely monitored out of the hospital and which women have severe disease requiring admission and close surveillance [5].

A same-day life-saving test to rule out pre-eclampsia is currently being rolled out across the NHS. Known as placental growth factor (PLGF) testing, the new blood test is the first of its kind in the world and has already helped thousands of expectant mothers [5]. A study on women’s attitudes, beliefs and values about predictive screening revealed that the participants were enthusiastic about new and improved predictive and diagnostic tests, giving them much needed mental relief [14].

In terms of new drugs that are being developed as a new treatment for pre‑eclampsia, kynurenine and its ability to relax blood vessels and lower blood pressure is currently being investigated [15].

What can I do to help?

Pre-eclampsia can be a life-changing experience and many women are left with unanswered questions about why it may have happened to them or how to prevent it. But remember, you are not alone. There are support and research organisations available online including:

You may be looking for a way to make that same experience better for other mothers and expectant mothers like you. You can share the details of your experience and be a patient voice in pre‑eclampsia research projects. You can register your interest here.

Proper prenatal care is essential so don’t miss your appointments. Weighing in, checking your blood pressure, and testing your urine for protein, are important for detecting pre-eclampsia, and should take place at every prenatal visit. Do not be afraid to question your doctor if any of these tests are omitted.

A good prenatal diet full of vitamins, minerals, and basic food groups is important for any pregnancy, as is reducing consumption of processed foods, refined sugars, and caffeine. Eliminating alcohol and any medication not prescribed by a physician is essential. Speak with your healthcare professional before taking any supplements. Although there is no evidence that these healthy behaviours and choices impact pre‑eclampsia, they do optimise your health for the best pregnancy possible.

Summary

 Pre-eclampsia is a condition characterised by high blood pressure during pregnancy and after labour. Early symptoms include proteins in the urine, headaches and swollen hands or feet. At the moment, the only way to cure pre-eclampsia is to deliver the baby at 37 or 38 weeks of pregnancy. Medication lowering the blood pressure may also be prescribed. New potential treatments for pre-eclampsia are currently being investigated. It is important to manage and monitor the condition as it may cause serious side effects to the mother or baby.

Pre-eclampsia is still one of the leading causes of maternal and foetal morbidity and mortality. Despite active research efforts for many decades, its aetiology remains unclear. The research into pre-eclampsia lacks funding, research and understanding. I hope that this article will promote awareness of the condition and will encourage pregnant women to attend all their prenatal appointments and to have a good diet throughout their pregnancy. I also wish that this blog post will spark more interest in research of pre-eclampsia and its treatment.

References

  1. Pre-eclampsia. Tommy’s. https://www.tommys.org/pregnancy-information/pregnancy-complications/pre-eclampsia-information-and-support. Published 2021. Accessed December 16, 2021.
  2. Pre-eclampsia. nhs.uk. https://www.nhs.uk/conditions/pre-eclampsia/. Published 2021. Accessed December 16, 2021.
  3. Magee L, Khalil A, Kametas N, von Dadelszen P. Toward personalized management of chronic hypertension in pregnancy. Am J Obstet Gynecol. 2020. doi:10.1016/j.ajog.2020.07.026.
  4. Rana S, Lemoine E, Granger J, Karumanchi S. Preeclampsia. Circ Res. 2019;124(7):1094-1112. doi:10.1161/circresaha.118.313276.
  5. Shennan A, Beardmore Gray A. PLGF – What We Know. Evesham: Action on pre-eclampsia; 2021:3-4.
  6. Premature birth statistics. Tommy’s. https://www.tommys.org/pregnancy-information/premature-birth/premature-birth-statistics. Published 2021. Accessed January 4, 2022.
  7. Cosmi E, Fanelli T, Visentin S, Trevisanuto D, Zanardo V. Consequences in Infants That Were Intrauterine Growth Restricted. J Pregnancy. 2011;2011:1-6. doi:10.1155/2011/364381.
  8. National Institutes of Health. Preterm Birth Causes, Consequences, And Prevention. Washington: National Academies Press; 2007:313-345.
  9. National Institute for Health and Care Excellence, 2019. Hypertension in Pregnancy: Diagnosis and Management. NICE, pp.21-22.
  10. National Institute for Health and Care Excellence, 2021. Severe hypertension, severe pre-eclampsia, and eclampsia in critical care. NICE, pp.4-6.
  11. Mol B, Roberts C, Thangaratinam S, Magee L, de Groot C, Hofmeyr G. Pre‑eclampsia. The Lancet. 2016;387(10022):999-1011. doi:10.1016/s0140‑6736(15)00070-7.
  12. Zehnder J, Tantry U, Gurbel P. Nonresponse and resistance to aspirin. Up to Date. 2020:1-5.
  13. Bij de Weg J, Abheiden C, Fuijkschot W et al. Resistance of aspirin during and after pregnancy: A longitudinal cohort study. Pregnancy Hypertens. 2020;19:25‑30. doi:10.1016/j.preghy.2019.11.008.
  14. Ahmed S, Brewer A, Tsigas E, Rogers C, Chappell L, Hewison J. Women’s attitudes, beliefs and values about tests, and management for hypertensive disorders of pregnancy. BMC Pregnancy Childbirth. 2021;21(1). doi:10.1186/s12884-021-04144-2.
  15. Worton S, Pritchard H, Greenwood S et al. Kynurenine Relaxes Arteries of Normotensive Women and Those With Preeclampsia. Circ Res. 2021;128(11):1679-1693. doi:10.1161/circresaha.120.317612.
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