Implantation cramping can occur 8-10 days after ovulation. You shouldn't feel any implantation cramping after you've had a positive pregnancy test. In early pregnancy, you may also experience constipation or bloating that feels like gas pain or cramps.
As your baby grows, you may feel cramps on one or both sides of your abdomen or toward your back when you change positions. These ligament cramps are most common between 14-20 weeks, but can occur at any time.
Cramps can be a signal of a problem or just another sign of a stretching and growing uterus. Early on in the pregnancy, you may experience implantation cramping, when the fertilized egg implants in your uterus. As your baby grows, your expanding belly adds pressure on the muscles, joints, ligaments and surround organs. The ligaments surrounding and supporting your uterus stretch and this leads to cramping. At this stage, the support is coming from the ligaments but as you uterus gets larger, the pelvic bones will help to support it. All of these cramps are perfectly normal.
However, some cramps can signal a problem. Cramps accompanied by spotting or bleeding is a warning sign of a possible miscarriage or ectopic pregnancy. If you have any type of bleeding, call your doctor right away.