@Linnet
I am rh neg and I didn’t get anti D as my husband is also rh neg as are our two children.
Wondering if I should be worried about aliens though 🤔
You didn't get anti-D because your 2 children are RhD neg. Cord blood is tested after delivery, to see whether any foetal cells are circulating in the maternal blood, AND the foetal blood is tested to see whether or not it is RhD neg or pos.
If the baby is RhD neg, then no anti-D is required.
If the baby is RhD pos, AND there are foetal cells in the maternal blood, then the anti-D dose may have to be increased, depending on the count of foetal cells.
The blood labs pay no attention to what the husband's blood group is because a) he might not be the actual father (Happens) and b) even if he is RhD pos, he might be heterozygous (RhD/d) and pass on the d (RhD neg, or the absence of RhD) to any child, which would make them RhD neg too.
The concept of RhD neg people being a different species is absolutely laughable.
RhD is only ONE of many antigens in the so-called "Rhesus" system - there are currently at least 49 known antigens in this highly important system, which has now been renamed as the Rh system. www.ncbi.nlm.nih.gov/books/NBK2269/
It is also not the only antigen to cause haemolytic disease of the newborn - an ABO blood group incompatibility between the mother and foetus can do that too, IF the mother has, for some reason, produced IgG antibodies to the opposing blood antigen (group O will have antibodies to A and B, group A will have antibodies to group B and group B will have antibodies to group A.) This just happens without exposure to the antigen, BUT is usually the pentamer (5-unit) antibody, IgM, which cannot cross the placenta. A monomer (single unit), IgG is a secondary antibody and CAN cross the placenta.
Other members of the Rh system can also cause HDN if there is an incompatibility.
First babies CAN have HDN, if the mother has previously been exposed to blood antigens she does not have herself, either by transfusion or if there is prolonged exposure to foetal blood cells during her pregnancy - but yes, it was usually the 2nd pregnancy that would suffer from the antibodies made after the first pregnancy. Foetal blood is not supposed to enter the maternal bloodstream, but it sometimes does.
Anti-D is one of the strongest antibodies that we make, of the blood group antibodies - but it's not the only one that can cause problems.
Another Rh antibody that can cause HDN is anti-c, or anti-little c. Anti-c is mostly found in RhD positive people, as most RhD negative people have c in their antigen profile. www.ncbi.nlm.nih.gov/pmc/articles/PMC3710558/
A non-Rh antibody that can cause HDN is anti-Kell.
www.ncbi.nlm.nih.gov/books/NBK2270/
Now you all have far more info than you ever needed on how some blood group antigens and antibodies work - basic genetic diversity.
One more for the conspiracy theorists - there is actually a blood group out there that is so rare, only a handful of related people have it - the H group. This is an absence of the glycoprotein that supports the AB antigens so that a person with group H cannot even receive group O blood, as they will have antibodies to that too. Oddly enough, they're not aliens or a "different species of human"
either - they just have a genetic deletion that means they don't make that particular glycoprotein on their red blood cells.