Hi,
If you use IVF, only embryos that don't carry thal genes will be implanted, so there is no risk of the child being thal. Many parents use this method to avoid taking the risk of having a thal major child. With both parents carrying two alpha thal genes, it is very risky to conceive in the normal manner, as babies that inherit two alpha thal genes from each parent will not survive pregnancy, as they can't produce any useful hemoglobin.