When I am pregnant ,I have a small cyst with a size of 64mm on my right ovary..now my son was 21/2 years old?

Until now there is no problem with the cyst.but from 3 months I am getting periods for 15 days late. When I am scanned there found that the cyst of right ovary became larger of 11 cm of size.I am getting little pain at right side of down tummy.is it necessary to remove it or not. Give me any suggestion.