There are statistics and we will find them. As I have said before, denovo hypertension of late pregnancy is a "pot pourri", probably a mixture. Some are "closet" preeclamptics whose proteinuria would present at a later date but delivery may intervene (they probably have raised circulating antiangiogenic levels), some are pure gestational hypertensives of late pregnancy representing a population who will develop essential hypertension later in life. Then there are frank essential hypertensives, unknown prepregnancy, who have an exaggerated fall in BP early in pregnancy, or whose levels fall below the 140/90 mm Hg that we know is too high a cut off. Also, the literature contains studies where presence or absence of proteinuria was by dip stick, and this literature is therefore unreliable. Now you know why the literature on "gestational hypertension" can be contradictory.