It is not uncommon to experience brown discharge during the fifth month of pregnancy. In most cases, it is harmless and can be attributed to various factors such as implantation bleeding, cervical irritation, or old blood being expelled from the cervix. However, it is always important to consult your healthcare provider if you notice any unusual changes in your vaginal discharge, including an increase in amount, foul odor, or accompanying pain or discomfort. Your doctor will be able to evaluate your specific situation and provide appropriate guidance and care.