It is not uncommon for women to experience mild cramping or discomfort in the lower abdomen during early pregnancy, including at 4 weeks. This can be due to the stretching and expanding of the uterus as it accommodates the growing embryo. However, if you are experiencing a sharp or severe pain on your left side, it is important to consult with your healthcare provider. While it could still be related to normal pregnancy changes, there are other potential causes such as an ectopic pregnancy or ovarian cyst that need to be ruled out. Your healthcare provider will be able to evaluate your symptoms and provide appropriate guidance and treatment if necessary.