Anaphylaxis During Pregnancy

Prenatal Yoga Breathing

Anaphylaxis is a severe allergic reaction, caused by the release of allergic chemicals such as histamine from allergic cells such as mast cells. Causes of anaphylaxis include foods, medications such as penicillin and NSAIDs, latex and insect stings, and bites. Symptoms of anaphylaxis can include urticaria and angioedema, symptoms of asthma, nausea/vomiting and diarrhea, and low blood pressure.

Anaphylaxis can also occur during pregnancy, especially during labor and delivery, and can represent a special danger to the fetus, because low blood pressure related to anaphylaxis in the mother can affect blood flow to vital organs in the fetus, such as the brain and heart. Additional symptoms of anaphylaxis during pregnancy may include vaginal and vulvar itching, uterine cramps, and low back pain.

Causes of Anaphylaxis During Pregnancy

The causes of anaphylaxis during most of the pregnancy are the same as in a non-pregnant woman. However, during labor and delivery, there are unique causes of anaphylaxis that need to be considered. In a past review of 23 patients with anaphylaxis during pregnancy, 8 had anaphylaxis to penicillin and related antibiotics, 6 had anaphylaxis to latex, 1 had anaphylaxis to a bee sting, and the remainder had anaphylaxis to other various medications.

Another study showed that there is a prevalence of 2.7 cases/100,000 deliveries where antibiotics were the most common culprit. 

Penicillin and Related Antibiotics 

During labor and delivery, these medications represent the most common cause of anaphylaxis. Penicillin (and related antibiotics) is the drug of choice for the prevention of neonatal group B streptococcal (GBS) and other infections (such as prophylaxis during cesarean section) and is often given at the time of labor and delivery. While skin testing is the best way to diagnose penicillin allergy, this is not recommended during pregnancy, given the small chance of anaphylaxis that may occur as a result of testing. Avoidance of penicillin is preferable during pregnancy (with the use of an alternative non-penicillin antibiotic) unless there is no alternative, such as when the mother is infected with syphilis.

Latex Allergy

Latex allergy is also a common reason for anaphylaxis during labor and delivery. Pregnant women with a history of latex allergy should be evaluated prior to labor and delivery with the use of serum IgE ELISA testing, rather than skin testing to latex, given the small chance of causing anaphylaxis with skin testing. Latex-allergic pregnant women can then be given a latex-free environment for labor and delivery.

Treatment of Anaphylaxis During Pregnancy

Typically, the treatment for acute anaphylaxis during pregnancy is not different from that in non-pregnancy. Epinephrine is the treatment of choice, and low blood pressure should be treated aggressively with repeated doses of epinephrine (as needed), intravenous fluids, and other medications to maintain blood pressure. Low blood pressure in the mother can lead to low blood flow to vital organs in the fetus, especially the brain. Anoxic brain injuries can occur when blood flow is reduced to the fetus for more than 5 minutes.

The best treatment for anaphylaxis during pregnancy is the prevention of anaphylaxis in the first place. Therefore, allergists are extremely important in the care of pregnant women who have a history of anaphylaxis to foods, medications, latex, and stinging insect allergy. Testing for most allergies should be deferred during pregnancy or performed using blood testing, in order to minimize the potential for anaphylaxis as a result of skin testing.

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