A trace amount is usually fine, it's only once it gets over a certain level that they start to be concerned, and will send you for a blood test. I had PE with my first baby - my protein reading from basic urinalysis (dipstick) was 4+, which is quite high. Have not had PE with my other pregnancies - the chance decreases with each pregnancy, if you have the same partner. Apparently if you get a new partner, your chance goes back to being the same as with your first.