Amniotic Fluid Embolism (Anaphylactic Syndrome of Pregnancy)

Amniotic fluid embolism (AFE) is a dangerous and life-threatening complication that occurs during delivery or shortly after giving birth. Amniotic fluid embolism is very difficult to diagnose because the symptoms can be similar to other serious complications during childbirth. Its exact cause is unknown. AFE is very rare.


Amniotic fluid embolism is a severe allergic reaction to amniotic fluid getting into your bloodstream when you give birth.
Amniotic fluid embolism is a rare complication that involves a severe allergic reaction to amniotic fluid getting into your bloodstream when you give birth.

What is amniotic fluid embolism?

Amniotic fluid embolism (AFE) is a rare and life-threatening complication that occurs when a pregnant person gets amniotic fluid into their bloodstream just before, during or immediately after childbirth.

Amniotic fluid is the liquid that surrounds the fetus in your uterus during pregnancy. It’s made of mostly water but also contains fetal cells and tissue. For reasons that are mostly unknown, some people have a severe allergic response to amniotic fluid mixing with their blood.

An amniotic fluid embolism can lead to heart and lung failure, which causes several complications due to a lack of oxygenated blood in your body. This could include cardiac arrest (your heart stops beating). People with AFE may also bleed uncontrollably from their uterus or C-section incision.

AFE happens suddenly and is unpredictable. It’s extremely challenging to treat and requires emergency medical care.

Amniotic fluid entering your bloodstream is a normal part of the birthing process. In most people, it doesn’t cause an allergic reaction. Researchers aren’t entirely sure why some people react to amniotic fluid this way while others don’t.

AFE is also known as anaphylactic syndrome of pregnancy.


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How common is AFE in pregnancy?

AFE is rare. It affects 1 in every 40,000 deliveries in the United States and 1 in every 53,800 deliveries in Europe.

The symptoms of AFE are similar to other complications during childbirth, like uterine rupture, placental abruption and eclampsia. This makes it more difficult to diagnose AFE as the cause of the complication.

What increases your risk of amniotic fluid embolism?

Risk factors for AFE are hard to predict because it’s rare and hard to study. However, current research points to a few possible risk factors, including:


Symptoms and Causes

What are symptoms of amniotic fluid embolism?

Signs and symptoms of AFE develop suddenly and quickly. They’re similar to symptoms of other complications during pregnancy and childbirth, making the condition more challenging to detect. Possible symptoms include:

  • Shortness of breath or difficulty breathing.
  • Sudden drop in blood pressure.
  • Pulmonary edema (fluid in your lungs).
  • Abnormal heart rate.
  • Bleeding from your uterus, C-section incision or IV (intravenous) sites.
  • Fetal distress.
  • Agitation, confusion or sudden anxiety.
  • Chills.

What are the complications of amniotic fluid embolism?

AFE can cause serious complications for you and the fetus. For you, these include:

The fetus is at risk of complications depending on when an amniotic fluid embolism occurs. An emergency delivery may be necessary if symptoms begin before the fetus is born. Babies who are delivered once AFE has already begun are at risk for not getting enough oxygen. Lack of oxygen could cause impairments in their nervous system or brain.

What causes amniotic fluid embolism?

There isn’t a known cause of AFE. The placenta breaking down during labor or delivery may trigger an immune response in some people, leading to AFE. It’s not clear why this happens in some people and not others.


Can AFE happen during a C-section?

Yes. Amniotic fluid embolism can occur during vaginal and C-section deliveries.

Diagnosis and Tests

How do doctors detect amniotic fluid embolism?

Diagnosing amniotic fluid embolism is difficult because many of the symptoms can overlap with other serious medical conditions. Your provider will rule out other possible causes while working to diagnose amniotic fluid embolism. Amniotic fluid embolism typically occurs in labor or within 30 minutes of delivery. If you have AFE, you’ll need immediate treatment to avoid potentially fatal complications.

Your provider may diagnose AFE if the following symptoms are present:

  • Sudden drop in blood pressure.
  • Difficulty breathing.
  • Irregular heart rate or your heart stops beating entirely.
  • Excessive bleeding or severe hemorrhage with no explanation.

Healthcare providers classify amniotic fluid embolism into two stages:

  • Phase one: During this phase, there’s rapid respiratory failure (you can’t breathe due to lack of oxygen) and cardiac arrest. This phase has the highest fatalities.
  • Phase two: This is the hemorrhagic (caused by a hemorrhage) phase. During this phase, you could experience excessive and uncontrolled bleeding at your C-section incision or from your uterus (in the area where the placenta was attached).

Since AFE is a medical emergency, healthcare providers are working quickly and can’t rely on imaging or blood tests for a diagnosis. However, if you survive an amniotic fluid embolism, your provider may order the following tests:

Management and Treatment

How is amniotic fluid embolism treated?

Amniotic fluid embolism is an emergency. Treatment for this condition will need to happen very quickly to protect you and the fetus. Several methods your provider may use include:

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How can I prevent amniotic fluid embolism?

Unfortunately, there’s no way to prevent amniotic fluid embolism. Healthcare providers are still unsure why AFE happens and what exactly causes this condition.

One way to prepare for any kind of medical emergency is to develop a plan with your family and healthcare providers. Ask your healthcare provider about emergency situations and how your medical team approaches these situations.

This may be a part of your birth plan (a document you develop before giving birth with your wishes for the birth). Remember, your birth plan represents the ideal situation. If there is ever an emergency, your healthcare team will need to act accordingly to protect the health of you and the fetus.

Outlook / Prognosis

What’s the survival rate for AFE?

Because AFE is difficult to diagnose and dependent on so many factors, it’s challenging to assign a percentage to how many people die from the condition. Studies vary depending on how the data is collected, but the death rate may be as high as 60%.

What is the long term effects for people who survive?

It depends on how severely you react to AFE as well as your health history. There can be both physical and psychological side effects from amniotic fluid embolism. Some long-term effects could include:

  • Neurological damage that affects your memory or word recall.
  • Permanent heart damage.
  • Complications from stroke (if you had a stroke).
  • Kidney problems.
  • Anxiety, depression and feelings of guilt.
  • Post-traumatic stress disorder (PTSD).

A note from Cleveland Clinic

Amniotic fluid embolism (AFE) is a life-threatening complication that occurs during labor and delivery. It’s rare and happens suddenly and quickly. AFE is not well-understood and there’s nothing you can do to prevent it from happening. Medical researchers are also unsure why AFE happens to some people and not to others.

If you’re pregnant, your chances of developing AFE is very low. Discuss your concerns about this rare condition with your pregnancy care provider so they can help ease your worries. If you’ve survived AFE, you may have long-term physical or psychological side effects. Talk to your provider, partner or friends so they can support you in your recovery from AFE.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 10/19/2022.

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