28wks preg.i am always comfrtble to sleep on my right side. is this healthy for my baby? may this position cause reduced blood flow to my baby?

Only in theory: While in theory lying on the left side improves blood return to your heart and perhaps to the baby, the practical effect of this is minimal to non-existent in normal situations. Your doctor should advise you if circumstances might make this important, but meanwhile it is more important that you be comfortable and get your rest.