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What Are the Signs of an Allergic Reaction to Pregnancy?

By C.B. Fox
Updated May 17, 2024
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Though there are no true allergic reactions to a pregnancy itself, there are a number of conditions that can manifest as pregnancy allergies. These conditions may be caused by allergic reactions to certain pregnancy hormones or by an allergy-like response to the Rhesus (Rh) factor on a fetus’s red blood cells. The symptom of an allergic reaction to pregnancy caused by hormonal incompatibilities is usually persistent nausea. Reactions to an incompatible Rh factor may include jaundice, anemia, and brain damage in the fetus, sometimes leading to miscarriage. Other allergy symptoms such as hives, swelling, or rash, known as the pruritic urticarial papules and plaques of pregnancy (PUPPP) also occur during pregnancy

Hyperemesis gravidarum, a condition that is sometimes referred to by laymen as an allergic reaction to pregnancy, is a relatively uncommon condition that can be caused by sensitivity to a hormone known as human chorionic gonadotropin. The main symptoms of this allergy-like condition are severe nausea that won’t go away and frequent, often violent vomiting. In the past, this condition was severe enough that it caused the death of many women. Now, the use of intravenous fluids and the ability to administer nutrients make it possible for even severely ill women to give birth and recover.

The Rh blood factor can also cause symptoms similar to an allergy to pregnancy. The symptoms are only present when a mother with Rh- blood has been exposed to Rh+ blood, possibly from a previous pregnancy or a blood transfusion, and is carrying an Rh+ fetus. The primary symptoms for this disorder affect the unborn baby, as the mother’s body creates antibodies that attack and kill the baby’s red blood cells. The baby can develop a number of problems related to low blood count, including anemia, brain damage, cardiovascular damage, and death.

Another condition that could be considered an allergic reaction to pregnancy are PUPPP. The symptoms of this disorder are eczema, hives, swelling, and itchiness that can occur on the stomach and breasts or all over the body. The rash will often spread across the body and is blotchy and red in appearance. It is not known what causes this type of allergic reaction to pregnancy, though some theories suggest that it may be caused by an inflammatory response triggered by the rapid growth of the fetus or by the fetus’s deoxyribonucleic acid (DNA).

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Discussion Comments
By bear78 — On Sep 05, 2014

@turquoise-- Yes, allergies to the hormones produced during pregnancy or allergies to the fetus itself can lead to an abortion. There seems to be different degrees of symptoms. Mild allergic reactions cause issues like nausea. Slightly more serious symptoms are rashes and itching, although these can have other causes. And the very serious reaction would be an abortion.

Of course, not all abortions are caused by allergies. There are many other causes. A doctor can run the necessary tests to understand what's happening.

I actually think that it's wrong for people to think that they may be allergic to their own baby. That's not the case. The allergy is usually to a new hormone, either produced by the body for the first time, or produced by the child. And it happens to many women. I hope women don't get depressed over the fact that it happened to them, because it can really happen to anyone.

By turquoise — On Sep 04, 2014

Could an allergic reaction to pregnancy be a cause of some abortions? Could the body be rejecting the baby?

By donasmrs — On Sep 04, 2014

My mother had Rh blood factor with me. She has Rh- blood. My father has Rh+ and so do my brother and I. I think this condition causes problems after the first child. When pregnant with the first child, the mother is developing those antibodies so the baby is usually fine. But with the second child, the antibodies are ready to go and can attack the baby.

When my mother was pregnant with me, her second child, several doctors told her to get an abortion because I would most likely die. My mom refused saying that only God knows what will happen. She tells me know that she spent the entire nine months praying for my health and for me to be born alive and healthy. I was born, a very healthy girl in spring. My mom believes that I'm a miracle and the first thing she taught me when I was old enough to understand was the prayer she repeated during her pregnancy for my health.

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