what will happen if genes of thal a2 and hbd will come together in the newborn

If the fetus carries mild thalassemia intermedia, then how is the growth of that child..? Will it be normal like other thalassemia carriers..like me or my wife? Or will it has to be on medication to maintain healthy or normal life..? At any stage in the lifecycle of the child, can it create any other health issues or affect any parts of the body..? Please suggest..?

The biggest problem answering your questions is that there is not a lot of data on this combination.  Since HbD is a benign trait and the hemoglobin that is produced is normal and carries oxygen, it is unlikely that it could cause any type of severe issue when combined with beta thal trait. In most observed cases, the combination of beta minor and HbD leads to a mild condition that is often not even known by the carrier, unless testing takes place. I don't think it can be compared to beta intermedia, even in the cases where it does cause a mild intermedia state. This is not a condition that should greatly change the life of the carrier.