[Hopefull2009]

Ok...My brain has been working overtime today and I have a question...just sheer curiosity.

I know that they don't really know why some people are allergic to drugs and others aren't, even in the same family.

My question is, for drugs that the mother takes that crosses the placenta, if the baby is predispositioned through hereditary factors to have an allergy to that drug, can a baby have an allergic reaction independent of the mother in utero?

I know that allergic reactions don't usually occur with the first use of the allergen, but show up in the second....but let's say for giggles that a mother took the same drug, two different times in her pregnancy.

Is it possible?

[GrumpyRN63]

I would guess no since they have separate circulatory systems....???

[CT Pixie]

I don't know the answer to that question but if it IS the case, that might explain some of the sudden deaths of babies in utero that don't seem to have a specific reason for their demise. But I would think that the baby would have to pass during the time the med was taken.

Great..thanks, now I will be pondering that question instead of studying for my upcoming test (LOL).

[nightmare]

British studies on aborted fetal samples showed that from the second trimester onwards fetuses
are capable of producing an allergic reaction. The researchers hypothesize that the antigens from
the mother cross the placenta, or that the fetuses swallow IgE antibodies from the amniotic fluid.
But this isn’t enough proof for the medical community. “At this point there is no evidence that

avoiding high-risk foods during pregnancy adds any clinical benefit over avoidance while breastfeeding.

This is taken from an article "Why peanuts,why now" by Janice Paskey.

[workingforskies]

Just a guess mind you...

Most deaths from allergic reactions come from decreased O2 exchange from increased airway inflammation. As fetuses get their oxygen from the mother's blood instead of through direct exchange of air, I would not think the effects of a fetal allergic reaction would be quite as profound.

But who knows.

[SteveRN21]

IgM and IgA do not cross the placenta, both major players in immune reactions. IgG does, however. I believe some studies had shown that certain drug allergies may have some genetic link, or may relate to getting some IgG from mom, predisposing them to a weak reaction that builds over time.

[Hopefull2009]

Originally Posted by workingforskies

Just a guess mind you...

Most deaths from allergic reactions come from decreased O2 exchange from increased airway inflammation. As fetuses get their oxygen from the mother's blood instead of through direct exchange of air, I would not think the effects of a fetal allergic reaction would be quite as profound.

But who knows.

Very good observation....

It's a strange thought, isn't it?

[feisty]

This is my first time posting. I just wanted to respond to the following comment....

"Most deaths from allergic reactions come from decreased O2 exchange from increased airway inflammation. As fetuses get their oxygen from the mother's blood instead of through direct exchange of air, I would not think the effects of a fetal allergic reaction would be quite as profound."

Let me preface it by saying that I am still a student so I am just throwing out thoughts not actual experience. Please take it with a grain of salt.

If the allergic reaction referred to is anaphylaxis then airway inflammation isn't the only problem caused by this. We were taught that anaphylatic shock is a systemic problem that involves circulatory collapse, MODS, and possible DIC. If this is so then where the oxygen originates from matters little if it is not being distributed throughout the body.

Having said that....I am not very familiar with the immune system of a fetus or a newborn so I am not certain about their IgE production and mast cell activity. This is a great question to ponder and research. Thanks goes out to the original poster for putting it out there.

[Hopefull2009]

Originally Posted by feisty

Having said that....I am not very familiar with the immune system of a fetus or a newborn so I am not certain about their IgE production and mast cell activity. This is a great question to ponder and research. Thanks goes out to the original poster for putting it out there.

I'm a student as well, so I understand where you are coming from.

I think you are dead on by saying that oxygen coming from the mother isn't that important if it's not getting circulated in the fetus.

There wasn't any reason for me to post this, other than the fact that I am sitting here going over allergic reactions (and I have an interest in neonatal side of nursing) and then it hit me....if a baby can have an allergic reaction after birth...what about in utero?

[Jolie]

Originally Posted by Hopefull2009

I think you are dead on by saying that oxygen coming from the mother isn't that important if it's not getting circulated in the fetus.

An interesting discussion that I haven't jumped into yet, because frankly, I don't know the answer.

But regarding fetal oxygenation, remember that normal paO2 in the fetus is only about 35mmHg, far less than the normal of 80(+)mmHg in the healthy, transitioned newborn. The fetus lives in relative hypoxia without harm. Of course, circulation is still crucial, but in my experience, inadequate circulation in the fetus usually stems from cardiac abnormalities such as congenital defects or CHF secondary to hydrops. I am not aware of any cases of circulatory collapse secondary to anaphylaxis or DIC in the fetus.