What is the reason why some women still get there periods during pregnancy im so confused and need help asap if anyone can please help me :)?

Not regular periods: Women do not get their periods when they are pregnant. Occasionally, pregnant women have spotting or vaginal bleeding and need to be evaluated by their ob-gyn doctors to make sure that there is not a problem with the pregnancy. A women who has a normal-looking menstrual period, happening at the time when her period is due, is not pregnant.