If you have left-sided stomach pain in the middle of pregnancy, you need to observe whether the nature of the pain is serious or not, and you also need to observe the degree of the pain, because there are many causes of stomach pain, including stomach pain if you have gastroenteritis or indigestion, and stomach pain if you have signs of pre-eclampsia. If you have gastroenteritis, stomach pain will be accompanied by abdominal distension, diarrhea, nausea, vomiting, or loss of appetite, and if you have pre-eclampsia, your stomach will be tight and hard, and in severe cases, there will be vaginal bleeding. You should pay attention to rest and not to overexert yourself to avoid increasing the chance of miscarriage.