We no longer define preeclampsia at then end of pregnancy with a relative change in BP, eg, 60 diastolic to 75 diastolic or 100 systolic to 130 systolic. It is sometimes difficult to determine what baseline pressure to use. In addition, most that get seriously ill from preeclampsia will eventually reach 140/90. The panel that achieved this consensus for the diagnosis also stated that relative rises, particularly remote from term, shoud notbe ignored.
If you are at 26 weeks and your BP has increased from 90/60 to 120/75, I would be concerned. If Dopplers are also abnormal, I would be more concerned. You might want to know how much proteinuruia you have. 300 mg/24 hours is needed for the diagnosis of preeclampsia; but if you had 200 mg at 26 weeks, I would be concerned.