Do people with sickle cell trait have the same rate of increased risk in pregnancy?
No. The carriers or sickle cell trait individuals usually have normal pregnancies and the risks of pregnancy complications mentioned above are comparable to those of the average population.
Are there special precautions required by a sickle cell disease sufferer before she conceives?
Yes. If a SCD sufferer is planning to become pregnant, she should see her doctor, who will need to sort out a few things.
One will be to offer counseling regarding the potential problems and outcome. There will also be genetic counseling. Since a SCD sufferer will inevitably pass on a defective gene to the child, it is important that the status of the partner is established, in order to calculate the chances of the child being affected and to what degree.
For instance, if the father is neither a sufferer nor a carrier (i.e. he has normal haemoglobin), the child will inherit a defective gene from the mother and a normal gene from the father. This means the child will be sickle cell trait or a carrier. This and all the other possible permutations have to be discussed and fully understood.
The other important aspect to be dealt with is the mother's general health pre-pregnancy. One of the organs that sickle cell disease tends to affect is the kidneys. It is imperative therefore that kidney function is assessed, to ensure that they can take the extra strain placed on them by pregnancy.
Finally, it is important that the mother's overall health status is optimised, so she can start her pregnancy from a relatively healthy position.
What special measures do these women require during pregnancy?
Nothing can substitute meticulous antenatal care. Apart from the general measures that every pregnant woman benefits from, SCD sufferers will need regular screening of their renal (kidney) function, and checks for possible urinary tract infection and development of such complications as pre-eclampsia and liver function.
The single most important measure will be to monitor her haemoglobin (Hb) level. Many affected women will require blood transfusion, sometimes several times, during pregnancy.
Why is blood transfusion likely to be necessary for SCD sufferers?
These women are chronically anaemic and pregnancy will inevitably worsen this. Anaemia puts a strain on vital organs, including the heart, and weakens the individual. This has to be prevented as much as possible.
Moreover, by giving sufferers "normal" blood, the proportion of defective blood is reduced. This reduces the chances of sickling crises. Sickling could be potentially catastrophic in pregnancy as these episodes are directly responsible for many - if not most - of the fetal losses in sufferers.
If blood transfusion is that beneficial, why is it not given as a matter of course to every pregnant SCD sufferer?
One wishes solutions were that simple and straightforward!
Even though modem blood transfusion is extremely safe, problems remain. The potential for these problems increases with the number of transfusions.
The transmission of viral infections via blood transfusion has been virtually eliminated, but there is always a risk, however tiny this might be. That is why the universal wisdom of not to transfuse unless necessary still holds true.
There is also the virtually unpreventable risk of developing what are known as atypical antibodies as a result of repeated transfusions. These antibodies could affect the fetus to the extent of triggering preterm delivery and exchange transfusions at birth.
This means that transfusions should be offered and given only when a meticulous assessment shows that it is necessary.