Medial Weight Loss - Diethylpropion

I've been taking diethylpropion for almost two months as part of a medical weight loss program. I work out regualrly (3-4 times a week) and didn't have any issues with my menstrual cycle last month. I'm currently 3 days later than I usually am. Has anyone taken this medication before? I know one of the side effects is menstrul irregularity, just wondering how common it is.