It's generally considered that regular menstrual periods do not occur during pregnancy. Once conception occurs, your body starts to produce hormones like hCG (human chorionic gonadotropin), which help to maintain the pregnancy and stop the menstrual cycle. However, some women do report experiencing symptoms similar to a period, such as spotting or light bleeding, especially in the first trimester. This can sometimes be confusing, but it's not the same as a regular menstrual period.