Erythroblastosis fetalis / why ??? - exist

[ArchivalUser]

why first Rh+ve baby is safe in Rh-ve mother ? while others Rh+ve develop erythroblastosis fetalis ?

[ArchivalUser]

bc during delivery babies blood gets into the mothers blood, and if baby is Rh+ and momy is Rh negative, her body will produce AB against Rh, and next time when she gets pregnant to Rh+ baby, Rh IgG will cross placenta and baby will have EBF
thaw why u give RHogam

[ArchivalUser]

@ exist I think what you are trying to ask is that how can a baby stay safe in a mother who is Rh -ve and is supposed to have antibodies against babies Rh factor right? Why are only subsequent babies at risk ?

You are right the FIRST baby is totally safe because the mother has never been exposed to RH + blood before .

The mother develops the antibodies only AFTER the first delivery OR in abruptio placenta , miscarriage and abortion .Basically any condition that would cause the leakage of the baby's blood into the mother otherwise this Antigen does not cross the blood placenta barrier in a normal first pregnancy UNTIL its labour time and all the mothers uterine vessels rupture open and allow sort of contamination by fetal blood .

In clinical practice we give Rhogam nevertheless in ALL pregnancies but it has been polled that approximately 60 percent mothers lie about a previous pregnancy or are unaware of miscarriages that occurred very very early on in the pregnancy .So a little clinical perspective.

Thats my way of understanding.Anybody else who reads correct me if I am wrong.

[ArchivalUser]

you are absolutely right but it could happen that the first baby develops hemolysis if transplacental bleeding occurs during pregnancy and the baby still alive and this is rare condition.

please correct to me if I am wrong

[ArchivalUser]

@EXIST
During first exposure of Rh positive cells into maternal circulation,the maternal immune response mounted against the non self Rh positive antigen leads to production of IgM. Being high moleculer weight IgM cant cross placenta.
During subsequent exposure of the mother to the antigen(which usually occur during second pregnancy with Rh positive fetus) leads to amnestic response with rapid production of large amount of IgG. IgG crosses placenta and cause hemolysis in the fetus.
Hope this helps. :-)

[ArchivalUser]

@success@mle thank you

I was thought that but this is NOT TRUE, to switch from IgM to IgG needs short time.
so Rh-ve mother exposed to fetal Rh+ve will develop IgM which switch to IgG from the exposure to the blood of First baby.

[ArchivalUser]

@EXIST
I am sorry I meant the subsequent exposure occur during labour which leads to production of IgG.This is the best i could get.
Source :Williams obstetrics.
Please let me know if this is not correct and the reference too.

[ArchivalUser]

@success@mle

u r right but Anti Rh IgG does not occur only during labour, it occurs at any time there is transplacental bleeding even during pregnancy . and this is what I am talking about.

Let's see other guys what they say

[ArchivalUser]

@ exist Yes thats correct. Any second exposure would produce IgG,it could be abruptio,miscarriage, version,placenta previa,and.Delivery usually is a second exposure more commonly. A time IgG produced will cross placenta and dam fetal rbc.
Therefore amount of bleeding plays a role too.if there is excessive bleeding the amount of IgG produced will be more.As occur during delivery..
Even during antenatal period there is some IgG produced in small amount in Rh neg mother carrying Rh positive fetus.therefore the trend of giving anti D during antenatal period around 32 weeks, started