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HELLP Syndrome

HELLP syndrome is a very dangerous pregnancy complication for both the carrying parent and the baby. Symptoms of HELLP usually occur during the third trimester of the pregnancy or after the parent has given birth.

This article is pending medical review.


Written by Patricia Posea

Reviewed by Eva Muijtjens, Hannah Claes, Mariam Hamadeh

Edited by Juliëtte Gossens


HELLP syndrome is an acronym for Hemolysis (destruction of red blood cells), Elevated Liver enzymes, and Low Platelets (the little cell fragments in your blood that help in stopping a bleeding). It is a very dangerous pregnancy complication for both the carrying parent and the baby. Symptoms of HELLP usually occur during the third trimester of the pregnancy (between weeks 29 to 37) or after the parent has given birth (postpartum period). However, the development of the disease starts earlier, in the first trimester.


HELLP affects about 0.2-0.8% of pregnancies (1-3). The causes of HELLP are not well known, but the development of the disease is very similar to that of pre-eclampsia (2). Some studies suggest that HELLP is actually a complication of pre-eclampsia, but the evidence is still conflicting (1, 2). This is because in about 20% of pregnant people, HELLP syndrome develops spontaneously, without first having pre-eclampsia.


Pre-eclampsia is when the pregnant parent has a high blood pressure and protein in their urine - this can happen after 20 weeks of gestation or after they have given birth. Eclampsia is a more complicated form of this, in which seizures can occur. For more information on these, check out our article about pre-eclampsia.

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How Does HELLP Syndrome Develop?

HELLP syndrome and pre-eclampsia are thought to develop very similarly (we recommend reading this article first). The underlying mechanism is called “poor placentation”, which starts to develop in the first trimester. We will explain what poor placentation means right here.


The placenta is the new organ that your body grows during pregnancy: it acts as a “messenger” between the parent and the baby, and it forms gradually in the first trimester of pregnancy. The placenta is essential for the baby to grow and develop.

Within the wall of the uterus, there are certain arteries that are crucial in supplying the placenta with enough blood from the parent: the spiral arteries. The spiral arteries are basically the highway between the maternal circulation and the placenta. They ensure proper blood flow to and from the baby. This way, essential nutrients and oxygen are provided to the baby, and any wastes, such as carbon dioxide (CO2), are removed. That is why it’s so important that blood flows smoothly into the placenta. This is normally the case when the spiral arteries grow correctly in the first trimester: they have low resistance (easy flow) and high capacity (lots of blood).

But in pre-eclampsia and HELLP syndrome, these arteries don’t grow correctly. The placenta then develops poorly because it lacks the necessary oxygen for the metabolism of its cells. This is where the term "poor placentation" comes from. In this situation, the placenta starts secreting stress substances - inflammatory molecules, such as C-reactive protein (CRP), interleukins (IL), cytokines and others.


Overall, these substances will harm endothelial cells (endothelial means on the inside of blood vessels). In this case, they over-activate the parent’s immune system. This may result not only in hypertension, but also in the hallmarks of HELLP:

  • Hemolysis

    • Red blood cells that pass through blood vessels with damaged endothelial lining will get fragmented, so overall, HELLP patients have less circulating intact red blood cells and develop anemia.

    • This condition is called hemolytic anemia or intravascular hemolysis.

  • Elevated liver enzymes

    • In HELLP, a specific toxin is released from the harmed placenta, called placenta-derived FasL. This toxin will cause injury to liver cells. When this happens, the cells release all their contents, including specific liver enzymes which we can measure in the blood.

  • Low platelet count

    • Platelets are the cells that act as a bandage on damaged parts of a blood vessel

    • Damage to the endothelial cells, exposure to inflammatory substances, and increased Von Willebrand factor (a protein in our vessels that platelets need to stick to a vessel wall) lead to formation of microscopic blood clots in (very) small blood vessels.

    • This condition is called thrombotic microangiopathy.

What's the difference between HELLP and pre-eclampsia?

We said that HELLP and pre-eclampsia have similar mechanisms. But then, what is the difference between these two?

In HELLP, the disease is very severe and the stress put on the placenta is higher, which results in more inflammatory and toxic substances being released from the placenta. In other words, people with HELLP are generally “sicker” than people with pre-eclampsia. But this is often not an easy difference to tell.

Another difference between the two diseases is that HELLP can occur without a high blood pressure. Part of the definition of pre-eclampsia is high blood pressure, so you need that to get a diagnosis of pre-eclampsia, but not HELLP.

Symptoms & Complications

Symptoms can vary a lot. Usually, people become sick in the third trimester (between weeks 29 to 37) or within 7 days after delivery (1). Symptoms include:

  • Intense pain on the right upper side of the belly - this comes from liver distension

  • Dizziness

  • Nausea

  • Vomiting

  • Fatigue

  • Headache that does not resolve even with painkillers

  • Changes in eyesight

  • Yellow skin discoloration (jaundice)

A severe complication of HELLP is disseminated intravascular coagulation (DIC), which is seen in up to 60% of cases (2, 3). This is when blood clotting happens all throughout the body. Sometimes, this doesn’t really have an effect on the prognosis of the disease, because your body can still compensate for the loss of all these blood clotting substances that are used up in all of those blood clots (2). But in other cases, it’s life-threatening, because the body can no longer compensate. There are no blood clotting components left, so if there is damage somewhere in the body, the bleeding can’t be stopped. Small injuries are happening in your body all the time, without you even noticing! But people with DIC will start noticing. They can start bleeding from their skin, mucous membranes (such as in the mouth), and internal organs. If left untreated, this ultimately leads to something called multi-organ failure, which is essentially the body shutting down. This can lead to death.


For the baby, a primary complication of poor placentation and HELLP is a low birth weight (lower than expected for the number of weeks of pregnancy). When the pregnant person develops the hallmarks of HELLP, the baby is at risk of more complications, such as placental abruption, in which the placenta separates from the wall of the uterus. This leads to a lack of oxygen (hypoxia) for the baby and heavy bleeding for the carrying parent. Hypoxia is fatal for the baby, which is why an emergency delivery must be done. Most babies of parents with HELLP are born prematurely because of this.


It's important to contact your doctor or hospital as soon as you experience any of the above symptoms and feel that something is wrong. Treatment for HELLP is necessary in all circumstances, because this is a life-threatening situation for both you and the baby.

Causes of HELLP Syndrome

Causes for HELLP are not well-known at all, but what we know is that poor placentation in the first trimester of pregnancy is the driving factor (1-3). There are also some studied risk factors that put you at risk of developing HELLP:

  • Having a family history of HELLP or pre-eclampsia (meaning for example your mother or sister has also had HELLP)

  • Having had a previous pregnancy affected by HELLP or pre-eclampsia

Studies show that people with a history of HELLP or pre-eclampsia are at an increased risk of developing HELLP in a future pregnancy. This is an added risk ranging between 2-19%, though the risk of developing HELLP at all is fortunately very low.


There is not one single gene that is causing the development of HELLP. There are multiple gene variants that, put together, can increase the risk.


Ultimately, the development of HELLP depends on multiple factors, including genetic, environmental and personal ones.  

Diagnosis of HELLP

Your doctor will first ask questions about your symptoms and perform a thorough physical examination. Your blood pressure will also be measured. Some people have an increased blood pressure of more than140/90 mmHg, but that is not always the case in HELLP (1-3). Your doctor will probably also collect some blood, to check multiple values that can confirm or support a HELLP diagnosis:

  • How many red blood cells and white blood cells you have, including platelets

  • What your hemoglobin level is, which can show anemia  

  • How high your liver enzymes are (such as AST, ALT)

  • How high your bilirubin levels are, which is a red blood cell breakdown product processed in the liver (and which leads to yellowing of the skin if too high)

  • Creatinine levels, an indicator of kidney function which can become impaired due to high blood pressure

  • Blood coagulation studies

  • Urine studies (which can show increased protein content)

When the situation requires it, imaging studies such as ultrasound, CT scan or an MRI can also be performed, for example to locate any large bleeding in the body.


If caught early, HELLP syndrome can be managed and treated. Unfortunately, the mortality of HELLP is still high, up to 24% for the pregnant person and 37% for the baby. That’s why you should contact a doctor if you’re not feeling well during your pregnancy.

Treatment of HELLP Syndrome

HELLP syndrome is treated in hospitals that have intensive care units, because HELLP can make you incredibly sick and you might need intensive treatment. This treatment mainly consists of supporting your body’s normal function and minimizing the symptoms, using extra oxygen, managing blood pressure, and managing pain (3, 4). Sometimes, blood transfusions are needed.

Currently, the only real treatment for HELLP is delivering the baby as soon as possible (1, 3, 4). This can be difficult to decide, especially in cases when the baby is still premature and does not have a proper lung function yet. If you’re less than 34 weeks pregnant, doctors will often prescribe corticosteroids to help with the maturation of baby’s lungs (3-5).

If delivery is not performed as soon as possible, the pregnant person is at a very high risk of further complications and death.


Overall, HELLP syndrome is a rare but very serious pregnancy complication. Scientists unfortunately don’t yet know a lot about what causes the disease or how to prevent it. Listen to your body – if something feels off, contact your doctor to come in for a check-up.



  1. Khalid F, Mahendraker N, Tonismae T. HELLP Syndrome. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023.

  2. Abildgaard U, Heimdal K. Pathogenesis of the syndrome of hemolysis, elevated liver enzymes, and low platelet count (HELLP): a review. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2013;166(2):117-23. DOI: 10.1016/j.ejogrb.2012.09.026

  3. Haram K, Svendsen E, Abildgaard U. The HELLP syndrome: clinical issues and management. A Review. BMC Pregnancy and Childbirth. 2009;9:8. DOI: 10.1186/1471-2393-9-8

  4. Katz L, de Amorim MMR, Figueiroa JN, e Silva JLP. Postpartum dexamethasone for women with hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome: a double-blind, placebo-controlled, randomized clinical trial. American Journal of Obstetrics and Gynecology. 2008;198(3):283.e1-.e8. DOI: 10.1016/j.ajog.2007.10.797

  5. Lam MTC, Dierking E. Intensive Care Unit issues in eclampsia and HELLP syndrome. International Journal of Critical Illness & Injury Science. 2017;7(3):136-41. DOI: 10.4103/IJCIIS.IJCIIS_33_17

Please note: the information we provide to you here is for educational purposes only. If you’re experiencing any discomfort or have any complaints or questions about your health, please contact your doctor or other relevant health professional. We don’t provide medical advice.


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