Circumvallate Placenta

Has anyone else ever had a circumvallate placenta? My OB told me today that it was seen on my anatomy ultrasound. I'm 19 weeks and this is my fourth pregnancy (didn't have an abnormal placenta with my first 3). And I'm kinda nervous and concerned about it. My doctor explained it to me today, i'm just interested in hearing personal stories from other mommies that have been diagnosed. Anybody have to deliver early because the placenta wasn't able to keep up the Increasing growth of the baby? Did anybody experience any bleeding in the third trimester? Did it cause low amniotic fluid?