Is Zerona Safe if You Are Trying to Get Pregnant?

I am not currently pregnant, but I do hope to be within the next year. I know that it is not a safe treatment while pregnant (which would be a silly thing to do while carrying a baby anyway!), and it is recommended not to do the treatment until after 6 weeks of giving birth. My concern is that it may have harmful effects to my reproductive system, or possibly to my future baby if I am pregnant within a few weeks or months of the treatment.