An amniotic fluid embolism develops suddenly and rapidly.
Signs and symptoms of an amniotic fluid embolism might include:
- Sudden shortness of breath
- Excess fluid in the lungs (pulmonary edema)
- Sudden low blood pressure
- Sudden circulatory failure (cardiovascular collapse)
- Life-threatening problems with blood clotting (disseminated intravascular coagulopathy)
- Altered mental status, such as anxiety
- Nausea or vomiting
- Rapid heart rate or disturbances in the rhythm of the heart rate
- Fetal distress, such as a slow heart rate
Why an amniotic fluid embolism occurs isn't well understood.
An amniotic fluid embolism occurs when amniotic fluid or fetal material enters the maternal bloodstream, possibly by passing through tears in the fetal membranes. It's likely that amniotic fluid contains components that cause an inflammatory reaction and activate clotting in the mother's lungs and blood vessels.
However, amniotic fluid embolisms are rare — and it's likely that some amniotic fluid commonly enters the maternal bloodstream during delivery without causing problems. It's not clear why in some cases this leads to an amniotic fluid embolism.
Further research on what causes amniotic fluid embolisms is needed.
Amniotic fluid embolisms are rare, which makes it difficult to identify risk factors. It's estimated that there are between 1 and 12 cases of amniotic fluid embolism for every 100,000 deliveries.
Research suggests that several factors might be linked to an increased risk of an amniotic fluid embolism, however, including:
- Advanced maternal age. If you're 35 or older at the time of your child's birth, you might be at increased risk of an amniotic fluid embolism.
- Placenta problems. If there are abnormalities in your placenta — the structure that develops in your uterus during pregnancy — you might be at increased risk of an amniotic fluid embolism. Abnormalities might include the placenta partially or totally covering the cervix (placenta previa) or the placenta peeling away from the inner wall of the uterus before delivery (placental abruption). These conditions can disrupt the physical barriers between you and your baby.
- Preeclampsia. If you have preeclampsia — high blood pressure and excess protein in the urine after 20 weeks of pregnancy — you might be at increased risk of developing an amniotic fluid embolism.
- Medically induced labor. Limited research suggests that certain labor induction methods are associated with an increased risk of amniotic fluid embolism. Research on this link, however, is conflicting.
- Operative delivery. Having a C-section, a forceps delivery or a vacuum extraction might increase your risk of an amniotic fluid embolism. These procedures can disrupt the physical barriers between you and your baby. It's not clear, however, whether operative deliveries are true risk factors for amniotic fluid embolisms or are used after the condition develops to ensure a rapid delivery.
- Genetics. Some experts believe that genetics might play a role in determining a woman's risk of amniotic fluid embolism.
An amniotic fluid embolism can cause serious complications for you and your baby.
If you have an amniotic fluid embolism, you're at increased risk of:
- Brain injury. Low blood oxygen can cause permanent, severe neurological damage or brain death.
- Lengthy hospital stay. Women who survive an amniotic fluid embolism often require treatment in the intensive care unit and — depending on the extent of their complications — might spend weeks or months in the hospital.
It's estimated that amniotic fluid embolisms cause up to 10 percent of maternal deaths in developed countries. Death can occur within an hour of the start of symptoms.
If you have an amniotic embolism, your unborn baby is at increased risk of a brain injury due to a lack of oxygen. The condition can also be fatal for babies.