Apart from humans and our close relatives, the
only animals that menstruate are elephant
shrews and certain bats. Why did it only evolve
in these species? Please I need ur views...
www.bbc.com/earth/story/20150420-why-do-women-have-periods

I got my first period when I was only 11.
In the first few years, my periods were not only
a source of occasional embarrassment, they
were also excruciatingly painful. I would lie
curled up in my bed with a hot water bag,
unable to move or breathe, and I would wonder:
"why me?"
Of course, I wasn't the only one: most women
menstruate. But most other female animals
don't bleed outwardly like us. Even among
those that give birth to live young as we do,
only a handful of species menstruate.
So menstruation isn't just inconvenient and
unpleasant: it's also a mystery. Why do we
menstruate at all? And if it's such a good idea,
why don't other animals do it?
Menstruation is part of a woman's reproductive
cycle. Every month, in response to reproductive
hormones – mainly oestrogen and
progesterone – a woman's womb gets ready
for pregnancy.
Women lose 30 to 90 ml of fluid over 3-7
days of menstruation
The inner lining of the womb, known as the
endometrium, prepares for an embryo to
implant in it. The endometrium thickens,
divides into different layers and develops an
extensive network of blood vessels.
If the woman doesn't get pregnant,
progesterone levels begin to fall. The thick
endometrial tissue with its blood vessels then
begins to slough off, and passes out through
the vagina. This bleeding is menstruation.
On average, women lose 30 to 90 ml of fluid
over 3-7 days of menstruation. We know,
because scientists have given women pre-
weighed pads and tampons, and weighed them
again after use.
On the face of it, this seems like a rather
wasteful process. As a result, many people
have attempted to explain why we do it.
"Some of the early thoughts on menstruation
were that it was removing toxins from the
body," says Kathryn Clancy, an anthropologist
at the University of Illinois in Urbana.

I think menstruation is a natural process of a women, where she gets ready for pregnancy right from the first menstrual cycle, which is a boon for all the women given by the nature. I am glad that I got to know more detail about it through your article, which also state the hormones which get changed during menstruation. Sometime, early menstrual cycle i.e. before 12 or late menstrual i.e. after 17 may be serious issues, which should be consulted by a good doctor, as it can cause problems like infertility. I have been also reading more about women hygiene from here.

Not true, my female dog has periods, since my compound is concreted she messes it up during those periods.