Can a girl's period just leave and be pregnant in the same room?

If the menstrual cycle is twenty-four or five days a time, menstruation time is seven days to be able to clean, wait until after menstruation clean into ovulation period, this time there may be pregnant in the same room. If menstruation 35 days once, menstruation three days clean, wait until menstruation clean after the same room from ovulation time is still relatively long, this time is generally not pregnant.