Hi welcome to HCMForum. It is not contraindication to have sex at this stage.
But it is not commen to have bleeding, it is called threatened abortion
. it could
be due to placenta previa
. to be confirmed by u.s.scaning. I advise you to consult
a gynacologist to prevent inevitable abortion. Avoid sex till you confirm the cause
of this problem. dont worry you will be fine.