What is Rh Disease
and what causes it?
Everyone is born with a specific blood type and an RH factor.
For example, you may have blood type "A" with an Rh factor of
"positive" (A+). This blood typing stays with you for life.
For full details on blood types, please seek information on Blood
In 85% of people, the Rhesus
Factor is positive (Rh+). For the other 15%, the Rh factor is negative
If a woman has Rh-negative blood
and the man has Rh-positive blood, then it is possible for problems to
Note: Rh Disease can only occur in women that have Rh Negative blood.
Note: If both the mother and baby are Rh negative, then there is no
Note: If both the mother and
natural father are Rh negative, then there is no risk because the child must
also be Rh negative. However, most
doctors prefer to presume that all Rh-negative women are at risk and will
treat her accordingly.
If an Rh-negative woman has a baby
that is Rh positive, then it is possible for some of the baby's blood to
enter into her system. This can happen under several circumstances:
During the birth,
Naturally (between 28 weeks and delivery),
During an amniocentesis,
At an abortion,
When a miscarriage occurs.
If the baby's Rh positive blood
enters a mother who is Rh Negative, then her immune system sees the cells as
'incompatible' or 'foreign' and will subsequently produce anti-rhesus
antibodies to try to destroy them for her own self-protection.
This may not seem like a big
problem, however, if she has another pregnancy where the baby is Rh positive,
then these antibodies that have formed will pass into the baby's bloodstream
via the placenta and attack the red blood cells of the baby.
Once these naturally created
anti-rhesus antibodies are present in the mother's bloodstream, they will
remain for life in the same way as antibodies for other diseases: chicken pox for example.