Do all women bleed in labor?

No. Some women may bleed with common lacerations that occur, others may have uncomplicated deliveries and not bleed. Blood may be seen naturally that comes from the placenta and the cutting of the cord.
Yes. There is always some bleeding associated with labor. Usually this occurs when the placenta detaches from the uterus. The blood vessels that communicated from the mothers circulation to the placenta bleed briefly until the uterus contracts down and seals them off. If the uterus is slow to firm up, medications and uterine massage can be used to speed the process along.