7wks and diagnosed with large ovarian cyst :(

I'm 7wks pregnant and had my first ultrasound today. Baby looked fine but my MD said I had a large ovarian cyst on the right side. He didn't seem too concerned saying we would just monitor and more than likely woukd go away on its own......but first time pregnant I'm pretty worried about the worst. Any experience with this? From what I read seems pretty common overall.