超聲波照得太多唔係咁好, 會影響BB生長...not that serious la. 超聲波do not use radiation, like X-ray, so it is not harmful.
But it is not necessary to do 超聲波 too often ~ so Mamas in most western countries do about 2-3 times throughout their pregnancies only ~ the same or less U/S scans if you are doing check-ups at public hospitals in HK only.
In HK, private doctors tend to do U/S for every prenatal check-up (to give you value for money) and most mothers will complain if they don't have U/S and the doctor will get bad comments about their service...