Rhesus

Blood tests is to find out your blood group (A, B, AB or O) and your rhesus status (positive or negative). 

Your rhesus factor is fixed by your genes. If you're rhesus positive (RhD positive), it means that a protein (D antigen) is found on the surface of your red blood cells. If you do not have the D antigen, you will be rhesus negative (RhD negative). 

Most people are rhesus positive.

http://www.babycentre.co.uk/a568837/what-is-my-rhesus-status-and-how-will-it-affect-my-pregnancy#ixzz4Y3vCTnaO

What does it mean if I'm Rhesus negative?

Rhesus status only matters if you are a rhesus-negative mum who is carrying a rhesus-positive baby. Your child will have inherited her rhesus-positive status from her rhesus-positive dad. 

If some of your baby's blood enters your bloodstream, your immune system may react to the D antigen in your baby's blood. It will be treated as a foreign invader and your body will produce antibodies against it. This is known as a sensitising event or being sensitised. 

Sensitising is not usually harmful if it is your first pregnancy. But it can cause problems if you become pregnant again with another rhesus-positive baby. The antibodies that your body made in your first pregnancy can quickly multiply, cross the placenta and attack the blood cells of your baby. 

The good news is that, because of routine injections of a substance called anti-D immunoglobulin (anti-D) to guard against the harmful effects of antibodies, complications are rare. 

However, if you are not treated with anti-D, the immune response in your second pregnancy will be stronger than the first pregnancy and can cause rhesus disease in your baby. Your antibodies start to attack your baby's blood cells during pregnancy and can carry on attacking them for a few months after the birth.

When your baby's blood cells are attacked, rhesus disease causes anaemia. If the anaemia becomes severe, it can lead to life-threatening problems for your baby, such as heart failure, fluid retention and swelling. 

After she’s born, your baby's liver won't be able to cope with the volume of blood cells that need breaking down. She may then become jaundiced, which is called haemolytic disease of the fetus and newborn (HDFN), or haemolytic disease of the newborn (HDN). 

In severe cases, HDFN can cause permanent brain damage and neurological problems in your baby, such as cerebral palsy, and physical or speech problems. 


http://www.babycentre.co.uk/a568837/what-is-my-rhesus-status-and-how-will-it-affect-my-pregnancy#ixzz4Y3w3Uby0

What do anti-D injections do?

Having an injection of anti-D can prevent your system from making antibodies. It's important to prevent antibodies from being made, because once they're produced, they stay in your blood forever. 

Anti-D works by rapidly destroying any fetal blood cells in your circulation before you can make antibodies. This means that you will not have antibodies in your system to cause haemolytic disease (HDFN) in this or your next pregnancy. 

http://www.babycentre.co.uk/a568837/what-is-my-rhesus-status-and-how-will-it-affect-my-pregnancy#ixzz4Y3vlxeXL