This is possible if you had unprotected sex. Otherwise the hormones can work a real number on certain women. As you get older, it gets worse. That is why there are products like Midol, which I can't take, as I get a bad reaction. Keep close track on a calender not only of period but of mood swings, at my age, never know when it is going to hit me, but if younger and pretty regular, you can pretty well predict how mood will change