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whyyou- t1_j1q06cz wrote

Depends; ABO incompatibility is not really an issue, Rh incompatibility is more serious but only if the mother negative and has been previously exposed to Rh(+) antigen (a previous pregnancy, blood transfusions). If the mother has been exposed and mother / baby are incompatible (mother negative, baby positive) it can lead to hemolytic disease of the fetus an autoimmune disease that breaks down the fetus blood cells and can be so severe to cause intrauterine death.

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kkngs t1_j1q781q wrote

Right. There is a shot they give to mothers in this situation, called RhoGAM, to help prevent the moms developing permanent antibodies.

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nicnoog t1_j1ro7o6 wrote

Shot is only for Anti-D, I unfortunately am anti-K - it's quite the faff when pregnant.

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[deleted] t1_j1rsp7r wrote

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No-Owl-295 t1_j1rg688 wrote

Which only works if her body did not form antibodies yet. If she already has antibodies and the fetus survives the first few weeks, they usually need several intra-uterine blood-transfusions.

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[deleted] t1_j1rp4ab wrote

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Hockeygoalie35 t1_j1tekzy wrote

I was an RH Disease baby. Needed several blood transfusions while still in the uterus, was born 10 weeks premature for further transfusions.

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ModlrMike t1_j1qaupw wrote

All Rh- pregnant women are given RHIg (WinRho, Rhogam etc) to minimize the chance that there is Rh incompatibility. While it is possible to assume that there will be no issues when both parents are Rh-, it is generally accepted practice to immunize the mother just the same. This page from Cleveland Clinic has a good explanation of the issue:

https://my.clevelandclinic.org/health/diseases/21053-rh-factor

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Voctus t1_j1qpyn0 wrote

Where I live they find out the fetus’s blood type and check for mismatch. There is enough fetal dna floating around in the mother’s blood to check things like blood type, gender, and chromosomal abnormalities (like Down’s syndrome).

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CartographerMore9712 t1_j1roe1t wrote

I work in a blood bank. From when the mother is greater than 12weeks gestation we can test the free fetal Dna is her blood to predict the baby’s Rh status. Only the women with predicted Rh positive babies will then receive the RhIg injection. With us the mothers will receive the RhIg injection routinely at 28weeks gestation but they will also receive it for any potential sensitising event throughout the pregnancy such as abdominal trauma or pv bleeds.

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Jimboats t1_j1rsy16 wrote

I think this must be country-dependent. In the UK all Rh- women are given the injection. I mean, how can you be certain that the father is really the father of that child? Surely that must give rise to a non-zero number of cases where there is a high risk of a baby being exposed unnecessarily?

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ohdearitsrichardiii t1_j1rw3wu wrote

They don't care about the (potential) father's blood type, they can tell the fetus's blood type from the mother's blood sample. I'm Rh-, they could see when I was about 10 weeks pregnant that my kids were Rh+ so I got the serum

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CartographerMore9712 t1_j1s0vuo wrote

They do free fetal DNA testing in the Uk. The IGBRL in Bristol is one of the major testing centres there. They can predict the Rh status of the baby from the baby’s DNA circulating in the mothers blood. About 35-40% of Rh- mothers will have Rh- babies. I will say not all maternity hospitals avail of this test but it is available

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dangelem t1_j1qn79p wrote

Well blood types A, B, and AB produce mainly IgM antibodies which cannot cross the placenta so this is really only an issue when the mother is blood type O, which produces mostly IgG antibodies that can in fact cross the placenta. However I think the percentage of developing HDN is very low, something like 4%, and when it happens it is mild. Something about the baby’s antigens not being properly developed so the antibodies cannot properly bind to destroy the blood cells.

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onewilybobkat t1_j1t1gjp wrote

Just to add, look up James Anderson. He has an antigen that saved a ton of babies from being attacked by their mothers blood because it was incompatible. Complications can arise to do conflicting blood types.

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DisulfideBondage t1_j1pkugs wrote

Risk is low during normal pregnancy. The risk is elevated during labor. If the mother’s blood gets into the child’s bloodstream it can cause pathological jaundice as the child’s immune system attacks the foreign blood cells breaking down the hemoglobin, elevating bilirubin levels.

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AmbilevousMD t1_j1qnjg8 wrote

This is kind of the opposite of what usually happens. During pregnancy, fetal red cells can cross the placenta causing an immune reaction in Mom. The antibodies from this reaction cross the placenta and can attack fetal red cells. There is a spectrum of severity ranging from hydrops fetalis to clinically insignificant. The antibodies linger in fetal circulation after birth and subsequent red cell destruction can contribute to jaundice. You can test for the presence of these antibodies with a Coombs test.

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CartographerMore9712 t1_j1rpoqq wrote

It’s the opposite. Yes The risk is low during pregnancy and is more likely to occur during delivery but it’s the baby’s blood that passes into the mothers blood stream causing the mother immune system to produce antibodies against the baby’s blood. These antibodies can pass across the placenta and attack the baby’s blood cells causing them to be destroyed. It is then the subsequent pregnancies that the Fetus and baby are affected.

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[deleted] t1_j1pos3v wrote

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SillyStallion t1_j1ppfk7 wrote

HDN is correct but ABO incompatibility is generally mild. It is generally only clinically significant with c, D and K antibodies.

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Dramatic-Move8793 t1_j1stzyf wrote

If the mother has Rh negative blood and becomes pregnant with a baby who has Rh positive blood, the mother's body will see those Rh antigens as foreign particles and will try to fight it off. Typically the first pregnancy is okay. But the mother's body will have built up an immunity against the Rh antigen by the second pregnancy.

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SBG_Mujtaba t1_j1sypdh wrote

Depends, during first pregnancy, there might be no complications, other than may be IUGR, during second if the mother hasn’t been given immuno suppressant then she will develop anti bodies that causes issues in following pregnancies.

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runthereszombies t1_j1xok8e wrote

The most important consideration is the D antigen aka Rh antigen which doesn't affect the first pregnancy, as others have said. If mom is Rh- and dad is Rh+, there is a chance that the fetus is Rh+. During pregnancy and especially during childbirth or miscarriage, the mother and fetus exchange blood. Mom's body recognizes the fetus' Rh+ blood as foreign and generates antibodies against this factor. This won't affect the initial pregnancy. However, if mom gets pregnant again with an Rh+ baby, then the antibodies will cross the placenta and attack the baby's red blood cells, causing a disease called hemolytic disease of the newborn. Its a serious form of anemia that can kill the baby.

This is why Rh- moms are given Rhogam, an antibody against this antigen. The idea is that during that first pregnancy, the Rhogam will "hide" the Rh antigen from the mother's immune system, preventing the formation of those antibodies and protecting future pregnancies.

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