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Special measures for pregnancy in individuals with HbH disease

As mentioned before, those patients tend to have hemolytic anemia as a chronic problem. As such, they do not have iron deficiency, so iron is never required as a supplement. However, folic acid supplements are crucial because they have an exaggerated consumption of this in their bodies.

The minimum daily Folic acid dose should be 5 mg.

 

Prenatal diagnosis for alpha-­thalassemia

Prenatal diagnosis for alpha-thalassemia is available. The fetal status can be established through DNA studies preferably following CVS or placental biopsy near the end of the first trimester (eleven to thirteen weeks).

 

Genetic screening and counseling of parents is a pre-requisite, to determine the probabilities of the fetus being affected and the extent. Then the parents need to look at the permutations and what they would want to do in each possible eventuality.

 

As a general statement, both alpha-thalassemia trait (where individuals are healthy) and HbH disease (where there is chronic anemia but normal life expectancy) are compatible with continuing the pregnancy.

When the diagnosis is that of alpha-thalassemia major (all four genes missing or affected), the situation is a lot more difficult.

 

 

Carrying a pregnancy where the diagnosis for the fetus is alpha­-thalassemia major

The pregnancy itself is almost invariably associated with complications. The most difficult is pre-eclampsia, which can be exceptionally severe and life-threatening for the mother.

 

If, in spite of the above, she manages to carry on, delivery is another tricky time. The fetus usually suffers from edema (hydropsy) and vaginal delivery may be impossible. A cesarean section, possibly in the presence of severe pre-eclampsia, may in itself endanger the life of the mother. Add to all these, the fact the baby will survive for minutes, at most, hours.

 

This is one prenatal diagnosis that, on paper at least, should lead to termination of pregnancy. The final decision, of course, rests with the parents.

 

Inheriting  the defective gene from mother with alpha-thalassemia trait

The child will not necessarily inherit the defective gene. Since the mother contributes two of the four alpha genes (the father contributing the other two), and since as a ‘trait’, has two or three normal genes herself, she may very well contribute the normal ones.  If the father is not affected, this particular child will be unaffected.

 

As can be seen, there is an element of lottery on whether the child inherits the defective gene or not. The chances of what happens to the child depend on how many defective genes the mother is carrying as well as whether or not the father is also a carrier.

 

The pre-pregnancy or pre-test counseling is meant partly to deal with this issue carefully and in detail for each particular couple.

 

Measures required for delivery in alpha-thalassemia carriers

Pregnancies for carriers of alpha-thalassemia are largely routine affairs. This is, even if the baby inherits the defect.

 

The only exception is when the fetus ends up with alpha-thalassemia major (as discussed above). As such, no special measures are called for during pregnancy, other than folic acid and sometimes oral iron supplements.

 

Likewise, delivery does not call for any special measures.

 

 

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