I had menstrual-ish cramps from about the time of implantation to around 7 weeks. At first, they were a little different from my typical cramps (they felt like pinching in my sides), but before I confirmed I was pregnant I had convinced myself they were just a variation of pre-menstral cramps. Later they became more like typical menstrual cramps (which worried me at the time!), but here I am, 12 weeks pregnant. I still get some minor cramps sometimes.