Lower abdominal cramping is just one of those things that happen (yep—another one) when baby is growing in your belly. Doctors call it round ligament pain.
See, your uterus is getting bigger every day (so is baby!), and the muscles and ligaments supporting it are stretching out to accommodate the changes. That stretching can bring a bit of pain, especially when you change positions, cough or are particularly active. These mild aches and jabs are normal and may persist as your uterus continues to grow (sorry).
To get some relief, scale back the physical activity and avoid cramp-inducing positions. Also try a warm bath, or simply stretch out and kick up your heels—resting comfortably should ease the pain.
You needn’t worry unless the pain is severe, constant or accompanied by bleeding or other unusual signs. If you have any of these symptoms, call your doctor right away.