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Here's what has to happen for pregnancy
to occur after sexual intercourse.
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Sperm must swim up the vagina,
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through the cervical opening,
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upwards through the uterus,
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and into one of the two fallopian tubes.
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If an egg, released during
that month's ovulation, is in the tube,
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one sperm has a chance to fertilize it.
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Contraceptives are designed
to prevent this process,
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and they work in three basic ways.
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They block the sperm,
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disable sperm
before they reach the uterus,
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or suppress ovulation.
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Block is the simplest.
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Male and female condoms prevent
sperm from coming into contact
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with the vaginal space.
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That barrier is also why they,
unlike other contraceptive methods,
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are able to prevent transmission
of certain sexually transmitted diseases.
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Meanwhile, the diaphragm,
cervical cap, and sponge
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work by being placed over the cervix,
barricading the entrance to the uterus.
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These contraceptives are sometimes
called barrier methods
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and can be used with spermicides,
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an example of
the second category, disable.
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A spermicide is a chemical
that immobilizes and destroys sperm.
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Today's spermicides come as foam,
cream, jelly, suppositories,
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and even a thin piece of translucent film
that dissolves in the vagina.
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These products can be inserted directly
into the vagina before intercourse,
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or can be combined with block methods,
like a diaphragm or condom,
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for added proection.
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The third category
for preventing pregnancy
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works by suppressing the action of an egg
maturing in the ovary.
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If there isn't an egg available
in the fallopian tube,
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there's nothing for sperm to fertilize.
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Hormonal contraceptives,
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including the pill, the patch,
the Depo shot, and the vaginal ring
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all release synthetic versions of various
combinations of progesterone and estrogen.
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This hormone cocktail
suppresses ovulation,
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keeping the immature age
safely sequestered in the ovary.
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Synthetic progesterone also has a block
trick up its sleeve.
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It makes cervical mucus too thick and
sticky for sperm to swim through easily.
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There are other contraceptives that
use multiple approaches at the same time.
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For example, many IUDs,
or intrauterine devices,
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contain synthetic hormones
which suppress ovulation.
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Some also contain copper,
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which disable sperm while also making
egg implantation in the uterus difficult.
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Block, disable, or suppress.
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Is one strategy better than the other?
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There are differences, but a lot of it
has to do with how convenient
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and easy it is to use
each contraceptive correctly.
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For example, male condoms would be
about 98% effective
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if everyone used them perfectly.
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That 98% means if 100 couples correctly
used condoms for a year,
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two women would get pregnant.
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But not everyone uses them correctly,
so they're only 82% effective in practice.
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Other methods, like the patch and pill,
are 99% effective
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when they're used perfectly.
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But in practice, that's 91%.
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Spermicide is only 85% effective,
even with perfect usage,
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and just 71% effective with typical usage.
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Another important consideration in the
choice of contraceptives are side effects,
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which almost exclusively effect women
rather than men.
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Hormonal methods in particular
can cause symptoms like headaches,
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nausea,
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and high blood pressure,
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but they vary from woman to woman.
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That's why these methods
require a prescription from a doctor.
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The choice of contraceptive method
is a personal one,
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and what works best for you now
may change later.
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Scientists also continue to research
new methods,
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such as a male pill that would
prevent sperm production.
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In the meantime,
there are quite a few options
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to block sperm,
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disable them,
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or suppress eggs
and keep them out of reach.
Margarida Ferreira
Please, attention:
Line 2:03 - "immature egg" - not "immature age"
Line 1:34 - "protection"