bluedogbrush,
Generally atrial septal defects and patent foramen ovales are well tolerated during pregnancy. The biggest worry is the possiblity of a stroke or other embolism with the defect letting flow move from the right side of the heart to the left. While there are a few case reports, they are generally pretty rare and most likely nothing further needs to be done with you.
I would discuss the finding with your OB Gyn and go from there.
good luck