Humans are mammals, humans breastfeed their children just like any other mammals. We give birth to live offspring, we have hair on our body, etc etc. But the phenomenon of female humans discarding blood every month seems unique to Homo Sapiens alone. Or is it? If it is unique to humans only, why?
Well, to answer that we have to understand why women have periods.(Form 3 science class~~)
If a woman does not become pregnant during oestrus, the womb lining and unfertilised egg are discarded - this is menstruation, or 'having a period'.
There are reports about animals discharging blood during certain period of the month, which may lead some people to suggest the animal is having a period. Well, not exactly - the animal is ready to conceive, not getting rid of its womb lining after failing to conceive - that's one vital difference between us and our mammalian friends. And the volume of blood they shed is relatively low compared to humans.