ANSWER:
Such a thing is part of the physique of a woman and she can’t hide that in normal cases. 
As long as it is not too tight or see-through, this seems fine in Sha Allah 

Women, where i live, wear clothes in front of their sons, fathers,brothers that cover their chest and body but show outlines of breast, so one can see bulge of breast. The bulge/outline of breast is even more visible when they are sitting and even more if they are lying down and resting. Is this okay? Or such loose clothes should be worn that outlines of breast should not be visible at all?

Women clothing |