Welcome to HCM.
Since you have already consulted a physician and he has reassured you as well as prescribed medicines to correct the problem, you have nothing to worry.
Be assured that it will not affect the growth of your baby in any way, in pregnancy
Ask your wife to eat fresh green vegetables and fruits and take a glass of milk daily, in addition to daily regular meals.
Wishing your wife and baby in the womb all the best.
Dr. P. Mahesh