”About 85 % of people have the Rhesus factor in their red blood cells they are Rhesus positive. The other 15 % who lack the factor are Rhesus negative. A Rhesus positive mother who’s carrying a Rhesus positive baby may develop antibodies to her Rhesus baby’s Rhesus positive blood cells and injure them“.
Elizabeth’s blood group is Rhesus negative and her partner’s. Chris is Rhesus positive. Their second baby has a 50:50 chance of being Rhesus-negative however if Chris passes on a recessive Rhesus-negative gene. Their first baby was Rhesus positive so Elizabeth may have developed anti-Rhesus-positive antibodies. If this second baby is Rhesus positive, the baby’s red blood cells may be damaged by the antibodies. To prevent any damage, Elizabeth will have special care throughout pregnancy.
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Elizabeth’s first pregnancy went without a hitch. This is usual with first pregnancies where the mother has Rhesus-negative blood and the baby. Rhesus-positive (an incompatible pregnancy).
However, when fetal blood cells mix with maternal cells, for example during delivery, the mother’s blood becomes sensitized. When the RH factor from the baby’s blood enters the mother’s bloodstream, it acts as an antigen and stimulates the production of anti-Rhesus-positive antibodies. These will attack and destroy the blood cells of her next Rhesus-positive (incompatible) baby. This causes haemolytic disease of the newborn and infants affected with blood conditions ranging from mild jaundice to serious, possibly fatal, anaemia. Fetuses who develop the disease can often be saved by intrauterine blood transfusion.
Not all Rh-negative women with Rh-positive babies become sensitized, but there is no way of predicting which women will. All of these women, therefore, should have an Anti-D injection.
Women who are Rhesus negative are also given an Anti-D injection after the following.
Within 48 hours of delivering her first baby, Elizabeth was injected intra-muscularly with Anti-D (Rh immune-globulin) to help prevent the destructive antibodies from forming. Had this pregnancy miscarried, she would have also needed the injection, because her blood and that of the baby’s would have mixed.
Elizabeth is hoping that she will be only mildly affected by Rhesus incompatibility. However, if antibodies have already formed, the Rhogham injection will be ineffective. Therefore, Elizabeth’s blood will be monitored throughout her pregnancy. At each visit, Elizabeth will have a special specimen of blood taken to examine for increasing levels of antibodies. Only if they increase beyond a certain point is her developing baby in any danger. If increasing antibodies are noted, she will have an ultrasound scan at 18 weeks. This can check for the presence of fetal bilirubin (a by-product of red cell destruction) in the amniotic fluid.
In the third trimester, a direct test for the presence of bilirubin can be done by a process called cordocentesis. This will enable the doctors to assess the severity of the condition and determine whether blood transfusions are necessary.
If her antibody count remains low, Elizabeth will not require further special care during her pregnancy. However, if the count rises moderately, her baby may be induced early to prevent serious consequences. In this case, home birth is out of the question and she will need to deliver in a hospital with an experienced obstetric department. She will probably have a Caesarean section. In a very few cases, the baby has to be given a blood transfusion to replace its own blood cells which have become damaged during pregnancy.
”Elizabeth’s baby is likely to be fit and healthy, owing to the Anti-D injections and the special care she receives during pregnancy“.
Rhesus disease only occurs when a woman who has Rhesus-negative blood(symbolized by red minus signs in the picture) is pregnant with a Rhesus-positive.
(Symbolized by blue plus signs)baby. Most Rhesus-negative mothers carry their first babies without any problems, just as Elizabeth did. However, if they subsequently develop antibodies to Rhesus-positive blood (symbolized by green triangles in the pictures below) any babies that they have later could be at risk.
If the mother is not given an Anti-D injection within 48 hours of delivery, she may develop antibodies to Rhesus positive blood.
If she becomes pregnant with another Rhesus-positive baby, her antibodies may attack this baby’s red blood cells.