Can You Have Preeclampsia without High Blood Pressure?

  • 1st Revision: Tamara Yap
  • 2nd Revision: Pranitha Ven Murali[Linkedin]
  • 3rd Revision: Kaamya Mehta[Linkedin]

What is preeclampsia?

Preeclampsia is a blood pressure disorder in pregnancy which occurs after 20 weeks in women who have previously had normal blood pressure, commonly marked by hypertension and protein level in urine (proteinuria). 1 According to the American College of Obstetrics and Gynaecology (ACOG), the markers of preeclampsia are hypertension (≥140mmHg/90mmHg) without proteinuria, low platelet/thrombocyte count (thrombocytopenia), renal insufficiency, liver dysfunction, pulmonary oedema, unexplained headache which is unresponsive to treatment, and visual symptoms. (2) Preeclampsia is the most common pregnancy complication, and the number of cases has increased globally, contributing to approximately 50,000 maternal deaths annually.3 The condition affects approximately 5-8% of all pregnancies worldwide and is closely related to the morbidity and mortality of the mother and the baby.4 Preeclampsia that is treated improperly can cause convulsion, which is then diagnosed as eclampsia.4  

Causes of preeclampsia

Pregnant women will experience a number of changes during the time of their maternity, including an increase in blood volume to support the baby; hence, the mother’s body will adjust to managing the changes. However, in some cases, the body cannot adjust, which subsequently leads to the signs of preeclampsia.5

The cause of preeclampsia is up for debate due to the physiological disorder process associated with the symptoms (pathophysiology).6 Meanwhile, another study attributed the development of preeclampsia to the placenta, and the process (called pathogenesis) is proven clinically and pathologically.7 The placenta functions as an intermediary for carrying substances that the baby needs through the blood. If the placenta does not receive a sufficient amount of blood due to an imbalance in its arteries, the placenta responds by releasing chemicals that affect the blood vessels.5 Consequently, the mother’s blood vessels narrow abnormally with an unclear mechanism, and this vessel constriction then increases the mother’s blood pressure to circulate the blood needed by the baby. The constriction also affects other organs, such as the kidney, as it detaches the abnormal proteins in the urine.5 Pathogenesis is affected by various factors such as genetics, immunology, and other maternal factors that influence placental dysfunction.7 

Symptoms of preeclampsia

 Women with preeclampsia do not always present with hypertension and proteinuria, sometimes there are those without proteinuria. Therefore, the symptoms of preeclampsia are divided into two, namely, moderate and severe preeclampsia.(8) The symptoms can only be examined and confirmed by an expert or professional healthcare provider. 

For moderate preeclampsia’s symptoms, the blood pressure is 140/90 mmHg, the proteinuria dipstick check is +1 and other laboratory examinations- such as thrombocytopenia, liver function test, and creatinine- are normal. The physical examination is also clear and there are no signs of lung swelling (pulmonary oedema), brain dysfunction, or visual disturbances. Meanwhile, severe preeclampsia symptoms include: blood pressure of 160/110 mmHg; a proteinuria dipstick test of +3; a laboratory examination for thrombocytopenia of <100,000; the liver function test results are 2x normal; and creatinine is 1.1 mg/dL. These are also signs of pulmonary oedema as well as brain and visual dysfunction.8

When do symptoms show up?

An early attack of preeclampsia occurs between 20 - 34 weeks of pregnancy; late-attack preeclampsia develops after 34 weeks of pregnancy, as the placenta is fully formed within 18-20 weeks of pregnancy and still provides oxygen, nutrition and immunity to the baby continuously. 8,9 Moreover, preeclampsia does not only occur during pregnancy but can happen during childbirth and even postpartum depending on the time of development during the pregnancy.10

Other blood pressure disorders during pregnancy

Apart from preeclampsia, the other blood pressure disorders in pregnancy categorised by The National High Blood Pressure Education Program Working Group are: 

Chronic hypertension is marked by an increase in blood pressure to at least 140/90 mmHg or more. It is most commonly diagnosed before pregnancy, before 20 weeks of pregnancy or remains until 12 weeks postpartum, which is confirmed by the presence of proteinuria after 20 weeks of pregnancy.10

Meanwhile, the blood pressure in gestational hypertension increases to more than 140/90 mmHg and is first diagnosed during pregnancy without proteinuria.11 There is also a possibility of gestational hypertension turning into preeclampsia. The blood pressure returns to normal at 12 weeks postpartum when the last diagnosis is made.10 Furthermore, superimposed preeclampsia is marked by the early existence or sudden rise of proteinuria after 20 weeks of pregnancy with chronic hypertension that has been diagnosed before.10

Risk factors

The risk factors of preeclampsia are:(10)

  • First pregnancy (nullipara)
  • Pregnancy at an extreme age; specifically more than 40 years old.
  • Twin pregnancy
  • Obesity or high Body Mass Index (BMI)
  • Having preeclampsia in the previous pregnancy
  • History of medical conditions such as chronic hypertension, diagnosed with diabetes before pregnancy, kidney dysfunction, and autoimmune disorders that can aggravate preeclampsia
  • Genetics

Can you develop preeclampsia even if you have never had high blood pressure pre-pregnancy?

According to Atrium Health, pregnant women who have never experienced high blood pressure before might still encounter preeclampsia as not all pregnant women show the obvious symptoms. Therefore, it is crucial to detect it as early as possible.12

Diagnosis

Due to the effect of preeclampsia on several organs- such as the liver- nerves, blood and kidneys, to establish a preeclampsia diagnosis, several examinations need to be set out:13 namely, blood pressure, proteinuria, laboratory and imaging tests. 

  • Blood pressure

Blood pressure should be measured twice within a 4-hour interval.14

  • Proteinuria

Involves a preliminary examination by a trained healthcare provider using the dipstick test. The results are then compared to the reagent-reading strip by visual analysis.15

  • Laboratory and imaging tests

The International Society for the Study of Hypertension in Pregnancy (ISSHP) suggests that haemoglobin, platelet count, creatinine serum, liver enzymes, and uric acid serum should be measured in pregnant women to determine the occurrence of preeclampsia and organ dysfunction.14 Furthermore, UltraSonography (USG) and Doppler Velocimetry examination are needed regarding placenta condition and blood flow in the placenta.16

Treatment

According to the National Health Service’s (NHS) recommendation, preeclampsia treatment is divided into three categories: hospitalisation, antihypertensive therapy, and delivering the baby. In hospitals, women with preeclampsia will be monitored strictly, and their blood pressure will be checked regularly. Moreover, regular monitoring of urine samples, blood tests and ultrasound scans monitor the prognosis.  The baby’s condition is also examined frequently using ultrasound and stress detection tools like cardiotocography or Non-Stress Test (NST).17 

Therapy such as antihypertensive, which decreases blood pressure, and anticonvulsants to prevent seizure (eclampsia) are given during preeclampsia. Ultimately, the only remedy against preeclampsia is to deliver the baby, and this is recommended at 37 to 38 weeks of pregnancy as the baby is more viable. The delivery process, whether natural or caesarean, is based on the doctor’s recommendation.17

The monitoring lasts until the postpartum phase as there is a possibility for preeclampsia to occur during this phase.17 

Prevention

Preeclampsia prevention is divided into primary and secondary treatment, which includes controlled antenatal, lifestyle, nutrition and supplementation, as well as pharmacology therapy. The primary interventions are implemented in the general population with bed rest and activity reduction, monitoring nutritional intake (less salt consumption and more antioxidants like vitamin C and E). Meanwhile, secondary interventions are for high-risk populations, such as drug therapy administered by doctors.18

Complications

The most common complication of preeclampsia is eclampsia which is a convulsion or undescribable coma.19 However, preeclampsia also affects many organs; hence, there are complications in neurology such as a stroke, heart failure, swollen lungs and breathing failure. Moreover, there is also clotted blood in the liver, which will cause liver dysfunction, placental dysfunction (detachment of the placenta from the uterus, which could possibly cause death for the baby), visual dysfunction and kidney insufficiency.20

Summary

Preeclampsia is a blood pressure-related disorder in pregnancy, of which the cause is still debated. However, the placenta has become the main focus of the cause because of its function, which connects the blood of both mother and baby. Preeclampsia is characterised by an increase in blood pressure, proteinuria, and other organ dysfunction, which can only be examined by a trained healthcare professional in a clinic or hospital. Furthermore, preeclampsia is often found within 20-34 weeks of pregnancy; hence, this period can help to diagnose preeclampsia as there are other blood pressure disorders that happen in the pregnancy. 

The diagnosis of preeclampsia can only be confirmed by examining the blood pressure, laboratory and image tests as well as considering the risk factors of the women. Moreover, to treat preeclampsia, doctors usually suggest hospitalising the women affected by preeclampsia and giving them antihypertensive and or anticonvulsants. Therefore, due to its high prevalence, preventive actions are taken such as controlled antenatal, lifestyle, nutrition and therapy to avoid complications.

References

  1. Ghulmiyyah L, Sibai B. Maternal Mortality From Preeclampsia/Eclampsia. Seminars in Perinatology. 2012 Feb;36(1):56–9.
  2. ACOG. Gestational Hypertension and Preeclampsia. Obstetrics &amp; Gynecology. 2020 Jun;135(6):e237–60. 
  3. Duley L. The Global Impact of Pre-eclampsia and Eclampsia. Seminars in Perinatology. 2009 Jun;33(3):130–7.  
  4. Jim B, Karumanchi SA. Preeclampsia: Pathogenesis, Prevention, and Long-Term Complications. Seminars in Nephrology. 2017 Jul;37(4):386–97.
  5. MedlinePlus. Preeclampsia: MedlinePlus Genetics [Internet]. MedlinePlus. 2016 [cited 2022 May 12]. Available from: https://medlineplus.gov/genetics/condition/preeclampsia/
  6. Myatt L, Roberts JM. Preeclampsia: Syndrome or Disease? Current Hypertension Reports. 2015 Sep 11;17(11). 
  7. Rana S, Lemoine E, Granger JP, Karumanchi SA. Preeclampsia. Circulation Research. 2019 Mar 29;124(7):1094–112. 
  8. Dhariwal NK, Lynde GC. Update in the Management of Patients with Preeclampsia. Anesthesiology Clinics. 2017 Mar;35(1):95–106.
  9. Targonskaya A. What Is a Placenta? Flo’s Guide [Internet]. Flo Health Inc. 2021 [cited 2022 May 12]. Available from: https://flo.health/pregnancy/giving-birth/labor-and-delivery/what-is-a-placenta
  10. Rosser ML, Katz NT. Preeclampsia: An Obstetrician’s Perspective. Advances in Chronic Kidney Disease. 2013 May;20(3):287–96.
  11. Sibai BM, Caritis S, Hauth J. What we have learned about preeclampsia. Seminars in Perinatology. 2003 Jun;27(3):239–46.
  12. Atrium Health. Preeclampsia: Catching It Early Makes All the Difference [Internet]. Preeclampsia: Catching It Early Makes All the Difference. 2019 [cited 2022 May 13]. Available from: https://atriumhealth.org/dailydose/2019/05/22/preeclampsia-catching-it-early-makes-all-the-difference
  13. Fox R, Kitt J, Leeson P, Aye CYL, Lewandowski AJ. Preeclampsia: Risk Factors, Diagnosis, Management, and the Cardiovascular Impact on the Offspring. Journal of Clinical Medicine. 2019 Oct 4;8(10):1625.
  14. Brown MA, Magee LA, Kenny LC, Karumanchi SA, McCarthy FP, Saito S, et al. Hypertensive Disorders of Pregnancy. Hypertension. 2018 Jul;72(1):24–43.
  15. Waugh JJS, Bell SC, Kilby MD, Blackwell CN, Seed P, Shennan AH, et al. Optimal bedside urinalysis for the detection of proteinuria in hypertensive pregnancy: a study of diagnostic accuracy. BJOG: An International Journal of Obstetrics and Gynaecology. 2005 Apr;112(4):412–7.
  16. NICE. Overview [Internet]. NICE. 2019 [cited 2022 May 13]. Available from: https://www.nice.org.uk/guidance/ng133
  17. NHS. Treatment [Internet]. nhs.uk. 2021 [cited 2022 May 13]. Available from: https://www.nhs.uk/conditions/pre-eclampsia/treatment/
  18. Meher S, Duley L. Interventions for preventing pre-eclampsia and its consequences: generic protocol. Cochrane Database of Systematic Reviews. 2005 Apr 20;CD005301(2).
  19. Olson-Chen C, Seligman NS. Hypertensive Emergencies in Pregnancy. Critical Care Clinics. 2016 Jan;32(1):29–41.
  20. Witcher PM. Preeclampsia: Acute Complications and Management Priorities. AACN Advanced Critical Care. 2018 Sep 15;29(3):316–26.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Dwi Tampubolon

Masters of Science - MSc Global Health Policy Student, The University of Edinburgh, Scotland

Dwi is a Research Assistant of Radiology Consultant and a Medical Writer.

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