If you are rhesus negative and your husband is rhesus positive, then your unborn child may inherit negative or positive blood – you wont know until birth. However if the mother is negative and the foetus happens to be positive (positive being dominant, negative recessive), this may cause problems for the foetus as well as any future pregnancies the mother may have. Problems can occur if the foetus’ positive blood manages to find it’s way into the mother’s bloodstream, either during pregnancy or labour, mixing with her negative blood. If this happens and it is not treated, the mother’s blood can create antibodies to attack the positive blood containing a ‘foreign’ component, causing anaemeia or in a worst case scenario, death for a foetus. This means that any future pregnancies the mother has where the foetus is again rhesus positive, her antibodies may cross the placenta and attack the foetus’ blood cells. Your obstetrician or midwife may organise a couple of blood tests throughout your pregnancy to monitor antibodies in your blood. It is important that the hospital where you birth your baby is aware of your rhesus negative blood, so they can test baby’s blood after the birth (from the placenta) to discover baby’s blood type. Should your baby have positive blood, you can choose to be given an “anti-D” injection within a couple of days following the birth. This prevents antibodies from forming. If you experience any bleeding during pregnancy or if you have an amniocentesis, miscarriage, ectopic pregnancy or termination, you need to make your primary medical carer aware of this as soon as possible, as these may all pose opportunities for the blood of the foetus to mix with that of the mother’s and it will be unclear in most of those cases as to which blood group the baby belonged to. If none of these things happen, in a normal pregnancy, you will not need ‘routine’ anti-D injections until after the birth, should the baby’s placenta come back as rhesus positive – and if you choose to. Some Obstetricians are now routinely giving Rh- women Anti-D injections without any blood tests to detect antibodies. However you might like to ask your doctor if this is really going to be effective or worthwhile if you have had no indication to suggest you have been bleeding. Not only is the shot of Anti-D a blood product (which involves risks in itself), but the chances that those routine injections (usually 2-3) will be given to you within 72 hours of possible bleeding – as required after possible exposure – which there has been no indication of bleeding anyway, is very slim. Your baby’s circulation is completely separate to yours so in a healthy pregnancy, the chance of the blood mixing is very, very slim.