Stomach pain during the second trimester of pregnancy is common and often caused by round ligament pain—when the ligaments supporting your belly stretch to accommodate your rapidly-growing bump. Try taking a warm bath or lying on your opposite side to relieve the discomfort. You’re also more likely to be gassy and constipated during pregnancy, thanks in part to your slowed-down digestion. Drink plenty of water and eat more fiber to stay regular. Be sure to check in with your doctor if stomach pain is accompanied by unusual vaginal discharge, especially spotting or bleeding, as well as pain when you urinate, regular cramping or lower back pain.