You must get your blood pressure checked.
It could be because of high blood pressure
that the bleed may occur.
In pregnancy the blood volume is high and when the pressure increases the small blood vessels of the nose burst open and they bleed.
You should take care and use normal saline nose drops and neosporin
ointment for local application in nose so that the nasal skin is moist and does not develop crusting which may lead to bleeding .
You should also get done bleeding time
, clotting time, Prothrombin time
In doubt do reply