Is Prolonged Use Of Progyluton Safe For Married Women?

after two months of my marriage, my wife not having menses and not pregnant. my doctor suggest "PROGYLUTON". my wife tokk it for 21 days and menses going to start after 7 days of medicine end. But now doctor again suggest that she will take it for 3 months. My question is that is it good for a married women? and what are its side effects?