| The menstrual cup was invented in the 1930s as an alternative to the
popular sanitary napkin, around the same time the first tampon was
patented.
The cup is inserted into the vagina, sitting low, and collects the
menstrual fluid. Newer cups, such as "Instead", have been designed
to stay higher up, near the cervix. Some brands are made of a material
like condom rubber and these have a hard ring around the top which the user
pulls the cup out by; others are made of thicker rubber and have a solid tube
attached to the bottom which the user pulls to remove the cup. There are
now both re-usable and disposable cups on the market.
The original cups were made of vulcanized rubber and were quite difficult to insert. These appeared on the market just before World War 2 and initially failed as a result of many factors: all rubber was supposed to
be used for war purposes, many doctors were against the idea of a woman
inserting things into her vagina with her fingers, and tampons and
disposable pads had just been introduced and were very popular.
In the 60s and 70s there was a resurgence of market interest in menstrual
cups, and many brands were put out for sale. This sales push also
failed: some say it was a result of media reluctance to advertise such a
product, and others say that women just weren't interested in an
environmentally friendly menstrual hygiene product at that time.
The 1980s brought the mainstream semi-acceptance of the cup. Women were
ready to insert objects into their vagina for the sake of convenience, the
medical sector believed the cup was a healthy and safe alternative to pads
and tampons, and the media was ready to run advertisements for such a
product.
Today, the "Keeper" is the most popular menstrual cup. It comes in
two sizes: A- for women who have had children, and B- for women who have not had children (the cup end of A is three millimetres wider than B), and
is made of natural gum rubber. The "Keeper" is reusable, and the cup is
designed to last ten years: at US$4 a year, that's pretty good value!
At www.mum.org (the Museum of Menstruation), anecdotal evidence tells
of the joys of the cup:
- Reduces landfill as a result of re-usability
- Users experience same freedom as tampon users (swimming, etc)
- The cup can be kept in all day (up to 12 hours) and will remain
hygienic (unlike tampons which can cause Toxic Shock Syndrome after 6 hours)
- The disposable cups can be left in during sex - but the Keeper and Diva cups, which are more rigid and sit lower in the vagina, have to be removed (thanks to anemotis)
- As the blood isn't exposed to the air, there is less odour than can be expected with pads or tampons
Points against using a menstrual cup:
- It takes a lot of practice to insert the cup properly without
leakage. The "Instead" company admits that cups can be "messy", espcially when removing, but also if not inserted properly
- They cup can hurt upon removal as a result of the suction in the
vagina
- The cup can cut and tear the vagina lining if the user isn't
careful
Update: It has been brought to my attention that there are now a few brands of reusable silicone cups on the market, and that they're better suited for gals who are allergic to latex. (Thanks to Lady_Day) | 
