Yes, Menstruation can also occur while pregnant, unless if she has menstruation disabilities.
i had mines while i was pregnant last year but i dont know if it could happen to anybody else
No, it's biologically impossible for a woman to menstruate while she is pregnant - a woman will only menstruate if she doesn't get pregnant during the last cycle. A woman can bleed during pregnancy for various reasons but this is fairly rare, chances are if you're menstruating you're not pregnant.
No women fail to menstruate. It comes naturally.
Women do not menstruate while pregnant. If you are certain you are pregnant, and begin bleeding, you should see a doctor immediately.
No, not every female gets her period. If talking exclusively of those who are biologically female there are those who don't have the anatomy to menstruate or their bodies don't produce the hormones needed to have a menstrual cycle. Pre-pubescent girls don't menstruate and women past menopause don't menstruate, also women who are pregnant won't menstruate during pregnancy (sometimes for longer if they breastfeed), and women who have a hysterectomy to remove the uterus.
If you were pregnant then you wouldn't menstruate at all. Menstruation only occurs if there is no pregnancy, if you menstruate you're not pregnant.
NO
Their body
It is biologically impossible to menstruate if you were pregnant.
Yes
If a girl thinks she is pregnant that doesn't mean that she is pregnant. A woman cannot menstruate while she is pregnant, thus if she menstruates she obviously isn't pregnant even if she thinks otherwise - although women can bleed during pregnancy this is uncommon, and not menstruation.